blas_example.cpp

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// @HEADER
// *****************************************************************************
//                           Sacado Package
//
// Copyright 2006 NTESS and the Sacado contributors.
// SPDX-License-Identifier: LGPL-2.1-or-later
// *****************************************************************************
// @HEADER

// blas_example
//
//  usage: 
//     blas_example
//
//  output:  
//     prints the results of differentiating a BLAS routine with forward
//     mode AD using the Sacado::Fad::DFad class (uses dynamic memory
//     allocation for number of derivative components).

#include <iostream>
#include <iomanip>

#include "Sacado_No_Kokkos.hpp"
#include "Teuchos_BLAS.hpp"
#include "Sacado_Fad_BLAS.hpp"

typedef Sacado::Fad::DFad<double> FadType;

int main(int argc, char **argv)
{
  const unsigned int n = 5;
  std::vector<double> a(n*n), b(n), c(n);
  std::vector<FadType> A(n*n), B(n), C(n);
  for (unsigned int i=0; i<n; i++) {
    for (unsigned int j=0; j<n; j++)
      a[i+j*n] = Teuchos::ScalarTraits<double>::random();
    b[i] = Teuchos::ScalarTraits<double>::random();
    c[i] = 0.0;

    for (unsigned int j=0; j<n; j++)
      A[i+j*n] = FadType(a[i+j*n]);
    B[i] = FadType(n, i, b[i]);
    C[i] = FadType(c[i]);
  }

  Teuchos::BLAS<int,double> blas;
  blas.GEMV(Teuchos::NO_TRANS, n, n, 1.0, &a[0], n, &b[0], 1, 0.0, &c[0], 1);

  // Teuchos::BLAS<int,FadType> fad_blas;
  // fad_blas.GEMV(Teuchos::NO_TRANS, n, n, 1.0, &A[0], n, &B[0], 1, 0.0, &C[0], 1);

  Teuchos::BLAS<int,FadType> sacado_fad_blas(false,false,3*n*n+2*n);
  sacado_fad_blas.GEMV(Teuchos::NO_TRANS, n, n, 1.0, &A[0], n, &B[0], 1, 0.0, &C[0], 1);

  // Print the results
  int p = 4;
  int w = p+7;
  std::cout.setf(std::ios::scientific);
  std::cout.precision(p);

  std::cout << "BLAS GEMV calculation:" << std::endl;
  std::cout << "a = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    for (unsigned int j=0; j<n; j++)
      std::cout << " " << std::setw(w) << a[i+j*n];
    std::cout << std::endl;
  }
  std::cout << "b = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    std::cout << " " << std::setw(w) << b[i];
  }
  std::cout << std::endl;
  std::cout << "c = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    std::cout << " " << std::setw(w) << c[i];
  }
  std::cout << std::endl << std::endl;

  std::cout << "FAD BLAS GEMV calculation:" << std::endl;
  std::cout << "A.val() (should = a) = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    for (unsigned int j=0; j<n; j++)
      std::cout << " " << std::setw(w) << A[i+j*n].val();
    std::cout << std::endl;
  }
  std::cout << "B.val() (should = b) = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    std::cout << " " << std::setw(w) << B[i].val();
  }
  std::cout << std::endl;
  std::cout << "C.val() (should = c) = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    std::cout << " " << std::setw(w) << C[i].val();
  }
  std::cout << std::endl;
  std::cout << "C.dx() ( = dc/db, should = a) = " << std::endl;
  for (unsigned int i=0; i<n; i++) {
    for (unsigned int j=0; j<n; j++)
      std::cout << " " << std::setw(w) << C[i].dx(j);
    std::cout << std::endl;
  }

  double tol = 1.0e-14;
  bool failed = false;
  for (unsigned int i=0; i<n; i++) {
    if (std::fabs(C[i].val() - c[i]) > tol)
      failed = true;
    for (unsigned int j=0; j<n; j++) {
      if (std::fabs(C[i].dx(j) - a[i+j*n]) > tol) 
  failed = true;
    }
  }
  if (!failed) {
    std::cout << "\nExample passed!" << std::endl;
    return 0;
  }
  else {
    std::cout <<"\nSomething is wrong, example failed!" << std::endl;
    return 1;
  }
}