MatrixMarket_util.hpp

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#ifndef __MatrixMarket_util_hpp
#define __MatrixMarket_util_hpp

#include <Teuchos_as.hpp>
#include <string>

namespace Tpetra {
  namespace MatrixMarket {

    namespace details {

      template<class Scalar>
      class SetScientific {
      public:
  typedef Scalar scalar_type;

  SetScientific (std::ostream& out) : 
    out_ (out), originalFlags_ (out.flags()) 
  {
    typedef Teuchos::ScalarTraits<scalar_type> STS;
    typedef typename STS::magnitudeType magnitude_type;
    typedef Teuchos::ScalarTraits<magnitude_type> STM;

    // Print floating-point values in scientific notation.
    out << std::scientific;

    // We're writing decimal digits, so compute the number of
    // digits we need to get reasonable accuracy when reading
    // values back in.
    //
    // There is actually an algorithm, due to Guy Steele (yes,
    // Java's Guy Steele) et al., for idempotent printing of
    // finite-length floating-point values.  We should actually
    // implement that algorithm, but I don't have time for that
    // now.  Currently, I just print no more than (one decimal
    // digit more than (the number of decimal digits justified
    // by the precision of magnitude_type)).
    //
    // We need to use STM's log10() rather than (say) std::log10
    // here, because STM::base() returns a magnitude_type, not
    // one of C++'s standard integer types.
    const magnitude_type numDecDigits = STM::t() * STM::log10 (STM::base());

    // Round and add one.  The cast to int should not overflow
    // unless STM::t() is _extremely_ large, so we don't need to
    // check for that case here.
    const magnitude_type one = STM::one();
    const magnitude_type two = one + one;
          // Cast from magnitude_type to int, since std::ostream's
          // precision() method expects an int input.
    const int prec = 1 + Teuchos::as<int> ((two*numDecDigits + one) / two);
    
    // Set the number of (decimal) digits after the decimal
    // point to print.
    out.precision (prec);
  } 

  ~SetScientific () {
    out_.flags (originalFlags_);
  }

      private:
  std::ostream& out_;

  std::ios_base::fmtflags originalFlags_;
      };

      // We define a class because template functions can't (in the
      // current C++ standard) have default template parameters.
      template<class Scalar, bool isComplex=Teuchos::ScalarTraits<Scalar>::isComplex>
      class ScalarAssigner {
      public:
  static void
  assign (Scalar& val,
    const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& real,
    const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& imag);
      };

      template<class RealType>
      class ScalarAssigner<RealType, false> {
      public:
  static void
  assign (RealType& val,
    const typename Teuchos::ScalarTraits<RealType>::magnitudeType& real,
    const typename Teuchos::ScalarTraits<RealType>::magnitudeType& imag)
  {
    // imag had better be zero.  We're ignoring it regardless.
    (void) imag;
    val = real; 
  }
      };

#ifdef HAVE_TEUCHOS_COMPLEX
      template<class MagType>
      class ScalarAssigner<std::complex<MagType>, true> {
      public:
  static void
  assign (std::complex<MagType>& val,
    const typename Teuchos::ScalarTraits<std::complex<MagType> >::magnitudeType& real,
    const typename Teuchos::ScalarTraits<std::complex<MagType> >::magnitudeType& imag)
  {
    val = std::complex<MagType> (real, imag);
  }
      };
#endif // HAVE_TEUCHOS_COMPLEX

      // \fn assignScalar
      // \brief val = S(real, imag).
      //
      // We have to template it because we don't know that S is a
      // complex type; if we write S(real,imag), the compiler will
      // complain if S is a real type.
      template<class Scalar>
      void 
      assignScalar (Scalar& val, 
        const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& real,
        const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& imag)
      {
  ScalarAssigner<Scalar>::assign (val, real, imag);
      }

    } // namespace details

    
    namespace {
      bool isSkew (const std::string& symmType) {
  return symmType.size() >= 4 && symmType.substr(0,4) == "skew";
      }

      bool isConj (const std::string& symmType) {
  return std::string::npos != symmType.find ("hermitian");
      }

      bool needsSymmetrization (const std::string& symmType) {
  return symmType != "general";
      }
    } // namespace (anonymous)

    template<class AdderType>
    class SymmetrizingAdder {
    public:
      typedef typename AdderType::index_type index_type;
      typedef typename AdderType::value_type value_type;
    
      SymmetrizingAdder (const Teuchos::RCP<AdderType>& adder, 
       const std::string& symmType) :
  adder_ (adder),
  symmetrize_ (needsSymmetrization (symmType)),
  conjugate_ (isConj (symmType)),
  skew_ (isSkew (symmType))
      {}
    
      void 
      operator() (const index_type i, 
      const index_type j, 
      const value_type& Aij) 
      {
  AdderType& theAdder = *adder_;

  theAdder (i, j, Aij);
  if (symmetrize_ && i != j) {
    typedef Teuchos::ScalarTraits<value_type> STS;
    const value_type Aji = skew_ ? 
      -(conjugate_ ? STS::conjugate(Aij) : Aij) : 
      (conjugate_ ? STS::conjugate(Aij) : Aij);
    theAdder (j, i, Aji);
  }
      }

      Teuchos::RCP<AdderType> getAdder() const {
  return adder_;
      }

    private:
      Teuchos::RCP<AdderType> adder_;
      bool symmetrize_;
      bool conjugate_;
      bool skew_;
    };

  } // namespace MatrixMarket
} // namespace Tpetra

#endif // __MatrixMarket_util_hpp