Sacado_ELRCacheFad_Ops.hpp

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// $Id$ 
// $Source$ 
// @HEADER
// ***********************************************************************
// 
//                           Sacado Package
//                 Copyright (2006) Sandia Corporation
// 
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
// 
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//  
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
// Questions? Contact David M. Gay (dmgay@sandia.gov) or Eric T. Phipps
// (etphipp@sandia.gov).
// 
// ***********************************************************************
//
// The forward-mode AD classes in Sacado are a derivative work of the
// expression template classes in the Fad package by Nicolas Di Cesare.  
// The following banner is included in the original Fad source code:
//
// ************ DO NOT REMOVE THIS BANNER ****************
//
//  Nicolas Di Cesare <Nicolas.Dicesare@ann.jussieu.fr>
//  http://www.ann.jussieu.fr/~dicesare
//
//            CEMRACS 98 : C++ courses, 
//         templates : new C++ techniques 
//            for scientific computing 
// 
//********************************************************
//
//  A short implementation ( not all operators and 
//  functions are overloaded ) of 1st order Automatic
//  Differentiation in forward mode (FAD) using
//  EXPRESSION TEMPLATES.
//
//********************************************************
// @HEADER

#ifndef SACADO_ELRCACHEFAD_OPS_HPP
#define SACADO_ELRCACHEFAD_OPS_HPP

#include "Sacado_ELRCacheFad_Expression.hpp"
#include "Sacado_cmath.hpp"
#include "Sacado_mpl_disable_if.hpp"
#include "Sacado_mpl_is_same.hpp"
#include <ostream>  // for std::ostream

namespace Sacado {
  namespace ELRCacheFad {

    //
    // UnaryPlusOp
    //

    template <typename ExprT>
    class UnaryPlusOp {};

    template <typename ExprT>
    class Expr< UnaryPlusOp<ExprT> > {
    public:

      typedef typename ExprT::value_type value_type;
      typedef typename ExprT::scalar_type scalar_type;

      typedef typename ExprT::base_expr_type base_expr_type;

      static const int num_args = ExprT::num_args;

      static const bool is_linear = true;

      Expr(const ExprT& expr_) : expr(expr_)  {}

      int size() const { return expr.size(); }

      template <int Arg>
      bool isActive() const { return expr.template isActive<Arg>(); }

      bool updateValue() const { return expr.updateValue(); }

      void cache() const {
  expr.cache();
      }

      value_type val() const {
  return expr.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr.getTangents(i, dots); }

      template <int Arg>
      value_type getTangent(int i) const {
  return expr.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr.isLinear();
      }

      bool hasFastAccess() const {
        return expr.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr.dx(i);
      }
 
      const value_type fastAccessDx(int i) const {
        return expr.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr.getArg(j);
      }

    protected:

      const ExprT& expr;
    };

    template <typename T>
    inline Expr< UnaryPlusOp< Expr<T> > >
    operator+ (const Expr<T>& expr)
    {
      typedef UnaryPlusOp< Expr<T> > expr_t;
      
      return Expr<expr_t>(expr);
    }

    //
    // UnaryMinusOp
    //
    template <typename ExprT>
    class UnaryMinusOp {};

    template <typename ExprT>
    class Expr< UnaryMinusOp<ExprT> > {
    public:

      typedef typename ExprT::value_type value_type;
      typedef typename ExprT::scalar_type scalar_type;

      typedef typename ExprT::base_expr_type base_expr_type;

      static const int num_args = ExprT::num_args;

      static const bool is_linear = true;

      Expr(const ExprT& expr_) : expr(expr_)  {}

      int size() const { return expr.size(); }

      template <int Arg>
      bool isActive() const { return expr.template isActive<Arg>(); }

      bool updateValue() const { return expr.updateValue(); }

      void cache() const {
  expr.cache();
      }

      value_type val() const {
  return -expr.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr.computePartials(-bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr.getTangents(i, dots); }

      template <int Arg>
      value_type getTangent(int i) const {
  return expr.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr.isLinear();
      }

      bool hasFastAccess() const {
        return expr.hasFastAccess();
      }

      const value_type dx(int i) const {
        return -expr.dx(i);
      }
 
      const value_type fastAccessDx(int i) const {
        return -expr.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr.getArg(j);
      }

    protected:

      const ExprT& expr;
    };

    template <typename T>
    inline Expr< UnaryMinusOp< Expr<T> > >
    operator- (const Expr<T>& expr)
    {
      typedef UnaryMinusOp< Expr<T> > expr_t;
      
      return Expr<expr_t>(expr);
    }

    //
    // AbsOp
    //

    template <typename ExprT>
    class AbsOp {};

    template <typename ExprT>
    class Expr< AbsOp<ExprT> > {
    public:

      typedef typename ExprT::value_type value_type;
      typedef typename ExprT::scalar_type scalar_type;

      typedef typename ExprT::base_expr_type base_expr_type;

      static const int num_args = ExprT::num_args;

      static const bool is_linear = false;

      Expr(const ExprT& expr_) : expr(expr_)  {}

      int size() const { return expr.size(); }

      template <int Arg>
      bool isActive() const { return expr.template isActive<Arg>(); }

      bool updateValue() const { return expr.updateValue(); }

      void cache() const {
  expr.cache();
  v = expr.val();
  v_pos = (v >= 0);
      }

      value_type val() const {
  return std::abs(v);
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (v_pos)
    expr.computePartials(bar, partials);
  else
    expr.computePartials(-bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr.getTangents(i, dots); }

      template <int Arg>
      value_type getTangent(int i) const {
  return expr.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr.hasFastAccess();
      }

      const value_type dx(int i) const {
        if (v_pos) return expr.dx(i); 
  else return -expr.dx(i);
      }
 
      const value_type fastAccessDx(int i) const {
        if (v_pos) return expr.fastAccessDx(i);
  else return -expr.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr.getArg(j);
      }

    protected:

      const ExprT& expr;
      mutable value_type v;
      mutable bool v_pos;
    };

    template <typename T>
    inline Expr< AbsOp< Expr<T> > >
    abs (const Expr<T>& expr)
    {
      typedef AbsOp< Expr<T> > expr_t;
      
      return Expr<expr_t>(expr);
    }

    //
    // FAbsOp
    //

    template <typename ExprT>
    class FAbsOp {};

    template <typename ExprT>
    class Expr< FAbsOp<ExprT> > {
    public:

      typedef typename ExprT::value_type value_type;
      typedef typename ExprT::scalar_type scalar_type;

      typedef typename ExprT::base_expr_type base_expr_type;

      static const int num_args = ExprT::num_args;

      static const bool is_linear = false;

      Expr(const ExprT& expr_) : expr(expr_)  {}

      int size() const { return expr.size(); }

      template <int Arg>
      bool isActive() const { return expr.template isActive<Arg>(); }

      bool updateValue() const { return expr.updateValue(); }

      void cache() const {
  expr.cache();
  v = expr.val();
  v_pos = (v >= 0);
      }

      value_type val() const {
  return std::fabs(v);
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (v_pos)
    expr.computePartials(bar, partials);
  else
    expr.computePartials(-bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr.getTangents(i, dots); }

      template <int Arg>
      value_type getTangent(int i) const {
  return expr.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr.hasFastAccess();
      }

      const value_type dx(int i) const {
        if (v_pos) return expr.dx(i);
  else return -expr.dx(i);
      }
 
      const value_type fastAccessDx(int i) const {
        if (v_pos) return expr.fastAccessDx(i);
  else return -expr.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr.getArg(j);
      }

    protected:

      const ExprT& expr;
      mutable value_type v;
      mutable bool v_pos;
    };

    template <typename T>
    inline Expr< FAbsOp< Expr<T> > >
    fabs (const Expr<T>& expr)
    {
      typedef FAbsOp< Expr<T> > expr_t;
      
      return Expr<expr_t>(expr);
    }

  }
}

#define FAD_UNARYOP_MACRO(OPNAME,OP,PARTIAL,VALUE)      \
namespace Sacado {              \
  namespace ELRCacheFad {           \
                  \
    template <typename ExprT>           \
    class OP {};              \
                  \
    template <typename ExprT>           \
    class Expr< OP<ExprT> > {           \
    public:               \
                  \
      typedef typename ExprT::value_type value_type;      \
      typedef typename ExprT::scalar_type scalar_type;      \
                  \
      typedef typename ExprT::base_expr_type base_expr_type;    \
                  \
      static const int num_args = ExprT::num_args;      \
                  \
      static const bool is_linear = false;        \
                  \
      Expr(const ExprT& expr_) : expr(expr_)  {}      \
                  \
      int size() const { return expr.size(); }        \
                  \
      template <int Arg>            \
      bool isActive() const { return expr.template isActive<Arg>(); } \
                  \
      bool updateValue() const { return expr.updateValue(); }   \
                  \
      void cache() const {            \
  expr.cache();             \
        v = expr.val();             \
  PARTIAL;              \
      }                 \
                  \
      value_type val() const {            \
  return VALUE;             \
      }                 \
                  \
      void computePartials(const value_type& bar,     \
         value_type partials[]) const {   \
  expr.computePartials(bar*a, partials);        \
      }                 \
                  \
      void getTangents(int i, value_type dots[]) const {    \
  expr.getTangents(i, dots); }          \
                  \
      template <int Arg>            \
      value_type getTangent(int i) const {        \
  return expr.template getTangent<Arg>(i);      \
      }                 \
                  \
      bool isLinear() const {                                           \
        return false;             \
      }                                                                 \
                                                                        \
      bool hasFastAccess() const {                                      \
        return expr.hasFastAccess();                                    \
      }                                                                 \
                                                                        \
      const value_type dx(int i) const {                                \
        return expr.dx(i)*a;            \
      }                                                                 \
                                                                        \
      const value_type fastAccessDx(int i) const {                      \
        return expr.fastAccessDx(i)*a;          \
      }                                                                 \
                  \
      const base_expr_type& getArg(int j) const {     \
  return expr.getArg(j);            \
      }                 \
                  \
    protected:                \
                  \
      const ExprT& expr;            \
      mutable value_type v;           \
      mutable value_type a;           \
    };                  \
                  \
    template <typename T>           \
    inline Expr< OP< Expr<T> > >          \
    OPNAME (const Expr<T>& expr)          \
    {                 \
      typedef OP< Expr<T> > expr_t;         \
                        \
      return Expr<expr_t>(expr);          \
    }                 \
  }                 \
}

FAD_UNARYOP_MACRO(exp,
      ExpOp, 
      a = std::exp(v),
      a)
FAD_UNARYOP_MACRO(log,
      LogOp, 
      a=scalar_type(1.0)/v,
      std::log(v))
FAD_UNARYOP_MACRO(log10,
      Log10Op, 
      a = scalar_type(1.0)/(std::log(scalar_type(10.0))*v),
      std::log10(v))
FAD_UNARYOP_MACRO(sqrt,
      SqrtOp, 
      a = scalar_type(1.0)/(scalar_type(2.0)*std::sqrt(v)),
      std::sqrt(v))
FAD_UNARYOP_MACRO(cos,
      CosOp, 
      a = -std::sin(v),
      std::cos(v))
FAD_UNARYOP_MACRO(sin,
      SinOp, 
      a = std::cos(v),
      std::sin(v))
FAD_UNARYOP_MACRO(tan,
      TanOp, 
      a = scalar_type(1.0)+std::tan(v)*std::tan(v),
      std::tan(v))
FAD_UNARYOP_MACRO(acos,
      ACosOp, 
      a = scalar_type(-1.0)/std::sqrt(scalar_type(1.0)-v*v),
      std::acos(v))
FAD_UNARYOP_MACRO(asin,
      ASinOp, 
      a = scalar_type(1.0)/std::sqrt(scalar_type(1.0)-v*v),
      std::asin(v))
FAD_UNARYOP_MACRO(atan,
      ATanOp, 
      a = scalar_type(1.0)/(scalar_type(1.0)+v*v),
      std::atan(v))
FAD_UNARYOP_MACRO(cosh,
      CoshOp, 
      a = std::sinh(v),
      std::cosh(v))
FAD_UNARYOP_MACRO(sinh,
      SinhOp, 
      a = std::cosh(v),
      std::sinh(v))
FAD_UNARYOP_MACRO(tanh,
      TanhOp, 
      a = scalar_type(1.0)/(std::cosh(v)*std::cosh(v)),
      std::tanh(v))
FAD_UNARYOP_MACRO(acosh,
      ACoshOp, 
      a = scalar_type(1.0)/std::sqrt((v-scalar_type(1.0))*(v+scalar_type(1.0))),
      std::acosh(v))
FAD_UNARYOP_MACRO(asinh,
      ASinhOp, 
      a = scalar_type(1.0)/std::sqrt(scalar_type(1.0)+v*v),
      std::asinh(v))
FAD_UNARYOP_MACRO(atanh,
      ATanhOp, 
      a = scalar_type(1.0)/(scalar_type(1.0)-v*v),
      std::atanh(v))

#undef FAD_UNARYOP_MACRO

//
// Binary operators
//
namespace Sacado {
  namespace ELRCacheFad {

    //
    // AdditionOp
    //

    template <typename ExprT1, typename ExprT2>
    class AdditionOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< AdditionOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = ExprT1::is_linear && ExprT2::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
      }

      value_type val() const {
  return expr1.val()+expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar, partials);
  if (num_args2 > 0)
    expr2.computePartials(bar, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return expr1.isLinear() && expr2.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i) + expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i) + expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;

    };

    template <typename ExprT1, typename T2>
    class Expr< AdditionOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = ExprT1::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
      }

      value_type val() const {
  return expr1.val() + expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr1.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;

    };

    template <typename T1, typename ExprT2>
    class Expr< AdditionOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = ExprT2::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
      }

      value_type val() const {
  return expr1.val() + expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr2.isLinear();
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;

    };

    //
    // SubtractionOp
    //

    template <typename ExprT1, typename ExprT2>
    class SubtractionOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< SubtractionOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = ExprT1::is_linear && ExprT2::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
      }

      value_type val() const {
  return expr1.val()-expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar, partials);
  if (num_args2 > 0)
    expr2.computePartials(-bar, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return expr1.isLinear() && expr2.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i) - expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i) - expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;

    };

    template <typename ExprT1, typename T2>
    class Expr< SubtractionOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = ExprT1::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
      }

      value_type val() const {
  return expr1.val() - expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr1.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;

    };

    template <typename T1, typename ExprT2>
    class Expr< SubtractionOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = ExprT2::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
      }

      value_type val() const {
  return expr1.val() - expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(-bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr2.isLinear();
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return -expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return -expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;

    };

    //
    // MultiplicationOp
    //

    template <typename ExprT1, typename ExprT2>
    class MultiplicationOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< MultiplicationOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        v1 = expr1.val();
  v2 = expr2.val();
      }

      value_type val() const {
  return v1*v2;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar*v2, partials);
  if (num_args2 > 0)
    expr2.computePartials(bar*v1, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        if (expr1.size() > 0 && expr2.size() > 0)
    return v1*expr2.dx(i) + expr1.dx(i)*v2;
  else if (expr1.size() > 0)
    return expr1.dx(i)*v2;
  else
    return v1*expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return v1*expr2.fastAccessDx(i) + expr1.fastAccessDx(i)*v2;
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type_1 v1;
      mutable value_type_2 v2;

    };

    template <typename ExprT1, typename T2>
    class Expr< MultiplicationOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = ExprT1::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
      }

      value_type val() const {
  return expr1.val()*expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar*expr2.val(), partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr1.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i)*expr2.val();
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*expr2.val();
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;

    };

    template <typename T1, typename ExprT2>
    class Expr< MultiplicationOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = ExprT2::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
      }

      value_type val() const {
  return expr1.val()*expr2.val();
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(bar*expr1.val(), partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr2.isLinear();
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.val()*expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return expr1.val()*expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;

    };

    //
    // DivisionOp
    //

    template <typename ExprT1, typename ExprT2>
    class DivisionOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< DivisionOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  a = scalar_type(1.0)/v2;
  v = v1*a;
  b = -v/v2;
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar*a, partials);
  if (num_args2 > 0)
    expr2.computePartials(bar*b, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
  if (expr1.size() > 0 && expr2.size() > 0)
    return expr1.dx(i)*a + expr2.dx(i)*b;
  else if (expr1.size() > 0)
    return expr1.dx(i)*a;
  else
    return expr1.val()*b;
      }

      const value_type fastAccessDx(int i) const {
        return  expr1.fastAccessDx(i)*a + expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type a;
      mutable value_type b;

    };

    template <typename ExprT1, typename T2>
    class Expr< DivisionOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = ExprT1::is_linear;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
  const value_type_1 v1 = expr1.val();
  a = scalar_type(1.0)/expr2.val();
  v = v1*a;
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar*a, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return expr1.isLinear();
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i)*a;
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*a;
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;
      mutable value_type v;
      mutable value_type a;

    };

    template <typename T1, typename ExprT2>
    class Expr< DivisionOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
  const value_type_2 v2 = expr2.val();
  v = expr1.val()/v2;
  b = -v/v2;
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(bar*b, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr2.dx(i)*b;
      }

      const value_type fastAccessDx(int i) const {
        return expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type b;

    };

    //
    // Atan2Op
    //

    template <typename ExprT1, typename ExprT2>
    class Atan2Op {};

    template <typename ExprT1, typename ExprT2>
    class Expr< Atan2Op<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  a = scalar_type(1.0)/(v1*v1 + v2*v2);
  b = -v1*a;
  a = v2*a;
  v = std::atan2(v1,v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar*a, partials);
  if (num_args2 > 0)
    expr2.computePartials(bar*b, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        if (expr1.size() > 0 && expr2.size() > 0)
    return expr1.dx(i)*a + expr2.dx(i)*b;
  else if (expr1.size() > 0)
    return expr1.dx(i)*a;
  else
    return expr1.val()*b;
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*a + expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type a;
      mutable value_type b;

    };

    template <typename ExprT1, typename T2>
    class Expr< Atan2Op<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  a = v2/(v1*v1 + v2*v2);
  v = std::atan2(v1,v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar*a, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i)*a;
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*a;
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;
      mutable value_type v;
      mutable value_type a;

    };

    template <typename T1, typename ExprT2>
    class Expr< Atan2Op< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  b = -v1/(v1*v1 + v2*v2);
  v = std::atan2(v1,v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(bar*b, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr2.dx(i)*b;
      }

      const value_type fastAccessDx(int i) const {
        return expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type b;

    };

    //
    // PowerOp
    //

    template <typename ExprT1, typename ExprT2>
    class PowerOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< PowerOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::pow(v1,v2);
  if (v1 == scalar_type(0.0)) {
    a = scalar_type(0.0);
    b = scalar_type(0.0);
  }
  else {
    a = v*v2/v1;
    b = v*std::log(v1);
  }
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0)
    expr1.computePartials(bar*a, partials);
  if (num_args2 > 0)
    expr2.computePartials(bar*b, partials+num_args1);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        if (expr1.size() > 0 && expr2.size() > 0)
    return expr1.dx(i)*a + expr2.dx(i)*b;
  else if (expr1.size() > 0)
    return expr1.dx(i)*a;
  else
    return expr1.val()*b;
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*a + expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type a;
      mutable value_type b;

    };

    template <typename ExprT1, typename T2>
    class Expr< PowerOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::pow(v1,v2);
  if (v1 == scalar_type(0.0)) {
    a = scalar_type(0.0);
  }
  else {
    a = v*v2/v1;
  }
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr1.computePartials(bar*a, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr1.dx(i)*a;
      }

      const value_type fastAccessDx(int i) const {
        return expr1.fastAccessDx(i)*a;
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;
      mutable value_type v;
      mutable value_type a;

    };

    template <typename T1, typename ExprT2>
    class Expr< PowerOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::pow(v1,v2);
  if (v1 == scalar_type(0.0)) {
    b = scalar_type(0.0);
  }
  else {
    b = v*std::log(v1);
  }
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  expr2.computePartials(bar*b, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return expr2.dx(i)*b;
      }

      const value_type fastAccessDx(int i) const {
        return expr2.fastAccessDx(i)*b;
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable value_type b;

    };

    //
    // MaxOp
    //

    template <typename ExprT1, typename ExprT2>
    class MaxOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< MaxOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::max(v1,v2);
  max_v1 = (v1 >= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0) {
    if (max_v1)
      expr1.computePartials(bar, partials);
    else
      expr1.computePartials(value_type(0.0), partials);
  }
  if (num_args2 > 0) {
    if (max_v1)
      expr2.computePartials(value_type(0.0), partials+num_args1);
    else
      expr2.computePartials(bar, partials+num_args1);
  }
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return max_v1 ? expr1.dx(i) : expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return max_v1 ? expr1.fastAccessDx(i) : expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable bool max_v1;

    };

    template <typename ExprT1, typename T2>
    class Expr< MaxOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::max(v1,v2);
  max_v1 = (v1 >= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (max_v1)
    expr1.computePartials(bar, partials);
  else
    expr1.computePartials(value_type(0.0), partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return max_v1 ? expr1.dx(i) : value_type(0.0);
      }

      const value_type fastAccessDx(int i) const {
        return max_v1 ? expr1.fastAccessDx(i) : value_type(0.0);
      }

      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;
      mutable value_type v;
      mutable bool max_v1;

    };

    template <typename T1, typename ExprT2>
    class Expr< MaxOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::max(v1,v2);
  max_v1 = (v1 >= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (max_v1)
    expr2.computePartials(value_type(0.0), partials);
  else
    expr2.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return max_v1 ? value_type(0.0) : expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return max_v1 ? value_type(0.0) : expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable bool max_v1;

    };

    //
    // MinOp
    //

    template <typename ExprT1, typename ExprT2>
    class MinOp {};

    template <typename ExprT1, typename ExprT2>
    class Expr< MinOp<ExprT1,ExprT2> > {

    public:

      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args1 = ExprT1::num_args;
      static const int num_args2 = ExprT2::num_args;
      static const int num_args = num_args1 + num_args2;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  int sz1 = expr1.size(), sz2 = expr2.size();
  return sz1 > sz2 ? sz1 : sz2;
      }

      template <int Arg> bool isActive() const {
  if (Arg < num_args1)
    return expr1.template isActive<Arg>();
  else
    return expr2.template isActive<Arg-num_args1>();
      }

      bool updateValue() const {
  return expr1.updateValue() && expr2.updateValue();
      }

      void cache() const {
  expr1.cache();
  expr2.cache();
        const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::min(v1,v2);
  min_v1 = (v1 <= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (num_args1 > 0) {
    if (min_v1)
      expr1.computePartials(bar, partials);
    else
      expr1.computePartials(value_type(0.0), partials);
  }
  if (num_args2 > 0) {
    if (min_v1)
      expr2.computePartials(value_type(0.0), partials+num_args1);
    else
      expr2.computePartials(bar, partials+num_args1);
  }
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
  expr2.getTangents(i, dots+num_args1);
      }

      template <int Arg> value_type getTangent(int i) const {
  if (Arg < num_args1)
    return expr1.template getTangent<Arg>(i);
  else
    return expr2.template getTangent<Arg-num_args1>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess() && expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return min_v1 ? expr1.dx(i) : expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return min_v1 ? expr1.fastAccessDx(i) : expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  if (j < num_args1)
    return expr1.getArg(j);
  else
    return expr2.getArg(j-num_args1);
      }

    protected:

      const ExprT1& expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable bool min_v1;

    };

    template <typename ExprT1, typename T2>
    class Expr< MinOp<ExprT1, ConstExpr<T2> > > {

    public:

      typedef ConstExpr<T2> ExprT2;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT1::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr1.size();
      }

      template <int Arg> bool isActive() const {
  return expr1.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr1.updateValue();
      }

      void cache() const {
  expr1.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::min(v1,v2);
  min_v1 = (v1 <= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (min_v1)
    expr1.computePartials(bar, partials);
  else
    expr1.computePartials(value_type(0.0), partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr1.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr1.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr1.hasFastAccess();
      }

      const value_type dx(int i) const {
        return min_v1 ? expr1.dx(i) : value_type(0.0);
      }

      const value_type fastAccessDx(int i) const {
        return min_v1 ? expr1.fastAccessDx(i) : value_type(0.0);
      }
      
      const base_expr_type& getArg(int j) const {
  return expr1.getArg(j);
      }

    protected:

      const ExprT1& expr1;
      ExprT2 expr2;
      mutable value_type v;
      mutable bool min_v1;

    };

    template <typename T1, typename ExprT2>
    class Expr< MinOp< ConstExpr<T1>,ExprT2> > {

    public:

      typedef ConstExpr<T1> ExprT1;
      typedef typename ExprT1::value_type value_type_1;
      typedef typename ExprT2::value_type value_type_2;
      typedef typename Sacado::Promote<value_type_1,
               value_type_2>::type value_type;
      typedef typename ExprT1::scalar_type scalar_type_1;
      typedef typename ExprT2::scalar_type scalar_type_2;
      typedef typename Sacado::Promote<scalar_type_1,
               scalar_type_2>::type scalar_type;

      typedef typename ExprT1::base_expr_type base_expr_type_1;
      typedef typename ExprT2::base_expr_type base_expr_type_2;
      typedef typename ExprPromote<base_expr_type_1,
           base_expr_type_2>::type base_expr_type;

      static const int num_args = ExprT2::num_args;

      static const bool is_linear = false;

      Expr(const ExprT1& expr1_, const ExprT2& expr2_) :
  expr1(expr1_), expr2(expr2_) {}

      int size() const {
  return expr2.size();
      }

      template <int Arg> bool isActive() const {
  return expr2.template isActive<Arg>();
      }

      bool updateValue() const {
  return expr2.updateValue();
      }

      void cache() const {
  expr2.cache();
  const value_type_1 v1 = expr1.val();
  const value_type_2 v2 = expr2.val();
  v = std::min(v1,v2);
  min_v1 = (v1 <= v2);
      }

      value_type val() const {
  return v;
      }

      void computePartials(const value_type& bar,
         value_type partials[]) const {
  if (min_v1)
    expr2.computePartials(value_type(0.0), partials);
  else
    expr2.computePartials(bar, partials);
      }

      void getTangents(int i, value_type dots[]) const {
  expr2.getTangents(i, dots);
      }

      template <int Arg> value_type getTangent(int i) const {
  return expr2.template getTangent<Arg>(i);
      }

      bool isLinear() const {
        return false;
      }

      bool hasFastAccess() const {
        return expr2.hasFastAccess();
      }

      const value_type dx(int i) const {
        return min_v1 ? value_type(0.0) : expr2.dx(i);
      }

      const value_type fastAccessDx(int i) const {
        return min_v1 ? value_type(0.0) : expr2.fastAccessDx(i);
      }

      const base_expr_type& getArg(int j) const {
  return expr2.getArg(j);
      }

    protected:

      ExprT1 expr1;
      const ExprT2& expr2;
      mutable value_type v;
      mutable bool min_v1;

    };

  }

}

#define FAD_BINARYOP_MACRO(OPNAME,OP)         \
namespace Sacado {              \
  namespace ELRCacheFad {           \
                  \
    template <typename T1, typename T2>         \
    inline Expr< OP< Expr<T1>, Expr<T2> > >       \
    OPNAME (const Expr<T1>& expr1, const Expr<T2>& expr2)   \
    {                 \
      typedef OP< Expr<T1>, Expr<T2> > expr_t;        \
                      \
      return Expr<expr_t>(expr1, expr2);        \
    }                 \
                  \
    template <typename T>           \
    inline Expr< OP< Expr<T>, Expr<T> > >       \
    OPNAME (const Expr<T>& expr1, const Expr<T>& expr2)     \
    {                 \
      typedef OP< Expr<T>, Expr<T> > expr_t;        \
                      \
      return Expr<expr_t>(expr1, expr2);        \
    }                 \
                  \
    template <typename T>           \
    inline Expr< OP< ConstExpr<typename Expr<T>::value_type>,   \
         Expr<T> > >          \
    OPNAME (const typename Expr<T>::value_type& c,      \
      const Expr<T>& expr)          \
    {                 \
      typedef ConstExpr<typename Expr<T>::value_type> ConstT;   \
      typedef OP< ConstT, Expr<T> > expr_t;       \
                  \
      return Expr<expr_t>(ConstT(c), expr);       \
    }                 \
                  \
    template <typename T>           \
    inline Expr< OP< Expr<T>,           \
         ConstExpr<typename Expr<T>::value_type> > >  \
    OPNAME (const Expr<T>& expr,          \
      const typename Expr<T>::value_type& c)      \
    {                 \
      typedef ConstExpr<typename Expr<T>::value_type> ConstT;   \
      typedef OP< Expr<T>, ConstT > expr_t;       \
                  \
      return Expr<expr_t>(expr, ConstT(c));       \
    }                 \
                  \
    template <typename T>           \
    inline typename             \
    mpl::disable_if<mpl::is_same<typename Expr<T>::value_type,    \
         typename Expr<T>::scalar_type>,  \
        Expr< OP< ConstExpr<typename Expr<T>::scalar_type>, \
            Expr<T> > >       \
        >::type           \
    OPNAME (const typename Expr<T>::scalar_type& c,     \
      const Expr<T>& expr)          \
    {                 \
      typedef ConstExpr<typename Expr<T>::scalar_type> ConstT;    \
      typedef OP< ConstT, Expr<T> > expr_t;       \
                  \
      return Expr<expr_t>(ConstT(c), expr);       \
    }                 \
                  \
    template <typename T>           \
    inline typename             \
    mpl::disable_if<mpl::is_same<typename Expr<T>::value_type,    \
         typename Expr<T>::scalar_type>,  \
        Expr< OP< Expr<T>,          \
            ConstExpr<typename Expr<T>::scalar_type> > > \
        >::type           \
    OPNAME (const Expr<T>& expr,          \
      const typename Expr<T>::scalar_type& c)     \
    {                 \
      typedef ConstExpr<typename Expr<T>::scalar_type> ConstT;    \
      typedef OP< Expr<T>, ConstT > expr_t;       \
                  \
      return Expr<expr_t>(expr, ConstT(c));       \
    }                 \
  }                 \
}


FAD_BINARYOP_MACRO(operator+, AdditionOp)
FAD_BINARYOP_MACRO(operator-, SubtractionOp)
FAD_BINARYOP_MACRO(operator*, MultiplicationOp)
FAD_BINARYOP_MACRO(operator/, DivisionOp)
FAD_BINARYOP_MACRO(atan2, Atan2Op)
FAD_BINARYOP_MACRO(pow, PowerOp)
FAD_BINARYOP_MACRO(max, MaxOp)
FAD_BINARYOP_MACRO(min, MinOp)

#undef FAD_BINARYOP_MACRO

//-------------------------- Relational Operators -----------------------

#define FAD_RELOP_MACRO(OP)           \
namespace Sacado {              \
  namespace ELRCacheFad {           \
    template <typename ExprT1, typename ExprT2>       \
    inline bool               \
    operator OP (const Expr<ExprT1>& expr1,       \
     const Expr<ExprT2>& expr2)       \
    {                 \
      return expr1.val() OP expr2.val();        \
    }                 \
                  \
    template <typename ExprT2>            \
    inline bool               \
    operator OP (const typename Expr<ExprT2>::value_type& a,    \
     const Expr<ExprT2>& expr2)       \
    {                 \
      return a OP expr2.val();            \
    }                 \
                  \
    template <typename ExprT1>            \
    inline bool               \
    operator OP (const Expr<ExprT1>& expr1,       \
     const typename Expr<ExprT1>::value_type& b)    \
    {                 \
      return expr1.val() OP b;            \
    }                 \
  }                 \
}

FAD_RELOP_MACRO(==)
FAD_RELOP_MACRO(!=)
FAD_RELOP_MACRO(<)
FAD_RELOP_MACRO(>)
FAD_RELOP_MACRO(<=)
FAD_RELOP_MACRO(>=)
FAD_RELOP_MACRO(<<=)
FAD_RELOP_MACRO(>>=)
FAD_RELOP_MACRO(&)
FAD_RELOP_MACRO(|)

#undef FAD_RELOP_MACRO

namespace Sacado {

  namespace ELRCacheFad {

    template <typename ExprT>
    inline bool operator ! (const Expr<ExprT>& expr) 
    {
      return ! expr.val();
    }

  } // namespace ELRCacheFad

} // namespace Sacado

//-------------------------- Boolean Operators -----------------------
namespace Sacado {

  namespace ELRCacheFad {

    template <typename ExprT>
    bool toBool(const Expr<ExprT>& x) {
      bool is_zero = (x.val() == 0.0);
      for (int i=0; i<x.size(); i++)
  is_zero = is_zero && (x.dx(i) == 0.0);
      return !is_zero;
    }

  } // namespace Fad

} // namespace Sacado

#define FAD_BOOL_MACRO(OP)            \
namespace Sacado {              \
  namespace ELRCacheFad {           \
    template <typename ExprT1, typename ExprT2>       \
    inline bool               \
    operator OP (const Expr<ExprT1>& expr1,       \
     const Expr<ExprT2>& expr2)       \
    {                 \
      return toBool(expr1) OP toBool(expr2);        \
    }                 \
                  \
    template <typename ExprT2>            \
    inline bool               \
    operator OP (const typename Expr<ExprT2>::value_type& a,    \
     const Expr<ExprT2>& expr2)       \
    {                 \
      return a OP toBool(expr2);          \
    }                 \
                  \
    template <typename ExprT1>            \
    inline bool               \
    operator OP (const Expr<ExprT1>& expr1,       \
     const typename Expr<ExprT1>::value_type& b)    \
    {                 \
      return toBool(expr1) OP b;          \
    }                 \
  }                 \
}

FAD_BOOL_MACRO(&&)
FAD_BOOL_MACRO(||)

#undef FAD_BOOL_MACRO

//-------------------------- I/O Operators -----------------------

namespace Sacado {

  namespace ELRCacheFad {

    template <typename ExprT>
    std::ostream& operator << (std::ostream& os, const Expr<ExprT>& x) {
      typedef typename Expr<ExprT>::base_expr_type base_expr_type;
      return os << base_expr_type(x);
    }

  } // namespace Fad

} // namespace Sacado


#endif // SACADO_CACHEFAD_OPS_HPP