sparse_example.cpp

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00001 // $Id$ 
00002 // $Source$ 
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00005 // 
00006 //                           Sacado Package
00007 //                 Copyright (2006) Sandia Corporation
00008 // 
00009 // Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
00010 // the U.S. Government retains certain rights in this software.
00011 // 
00012 // This library is free software; you can redistribute it and/or modify
00013 // it under the terms of the GNU Lesser General Public License as
00014 // published by the Free Software Foundation; either version 2.1 of the
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00019 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00020 // Lesser General Public License for more details.
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00030 // @HEADER
00031 
00032 // dfad_example
00033 //
00034 //  usage: 
00035 //     dfad_example
00036 //
00037 //  output:  
00038 //     prints the results of differentiating a simple function with forward
00039 //     mode AD using the Sacado::Fad::DFad class (uses dynamic memory
00040 //     allocation for number of derivative components).
00041 
00042 #include <iostream>
00043 #include <iomanip>
00044 
00045 #include "Sacado.hpp"
00046 
00047 // The function to differentiate
00048 template <typename ScalarT>
00049 ScalarT func(const ScalarT& a, const ScalarT& b, const ScalarT& c) {
00050   ScalarT r = std::log(b+1.)/std::sin(a);
00051 
00052   return r;
00053 }
00054 
00055 typedef Sacado::LFad::LogicalSparse<double,bool> FadType;
00056 
00057 int main(int argc, char **argv)
00058 {
00059   double pi = std::atan(1.0)*4.0;
00060 
00061   // Values of function arguments
00062   double a = pi/4;
00063   double b = 2.0;
00064   double c = 3.0;
00065 
00066   // Number of independent variables
00067   int num_deriv = 3;
00068 
00069   // Fad objects
00070   FadType afad(num_deriv, 0, a); // First (0) indep. var
00071   FadType bfad(num_deriv, 1, b); // Second (1) indep. var
00072   FadType cfad(num_deriv, 2, c); // Third (2) indep. var
00073   FadType rfad;                  // Result
00074 
00075   // Compute function
00076   double r = func(a, b, c);
00077 
00078   // Compute function and derivative with AD
00079   rfad = func(afad, bfad, cfad);
00080 
00081   std::cout << rfad << std::endl;
00082 
00083   // Extract value and derivatives
00084   double r_ad = rfad.val();     // r
00085   bool drda_ad = rfad.dx(0);  // dr/da
00086   bool drdb_ad = rfad.dx(1);  // dr/db
00087   bool drdc_ad = rfad.dx(2);  // dr/dc
00088 
00089   double tol = 1.0e-14;
00090   if (std::fabs(r - r_ad) < tol && drda_ad && drdb_ad && !drdc_ad) {
00091     std::cout << "\nExample passed!" << std::endl;
00092     return 0;
00093   }
00094   else {
00095     std::cout <<"\nSomething is wrong, example failed!" << std::endl;
00096     return 1;
00097   }
00098 }

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