MatrixSolves_lapack.cpp File Reference

Example of the simple linear solvers implemented for dense, banded and sparse matrix objects. More...

#include <cassert>
#include <Timer.h>
#include <Types.h>
#include <Utility.h>
#include <DenseLinearSystem.h>
#include <BandedLinearSystem.h>

Go to the source code of this file.

Functions
int	main ()

Detailed Description

Example of the simple linear solvers implemented for dense, banded and sparse matrix objects.

To begin with a simple matrix problem is solved. Then a penta-diagonal problem is solved using the dense, banded and sparse containers. The native linear Gaussian elimination solvers are used unless the PETSC_D/Z compiler options are used, in which case the linear solver phase calls the PETSc library as appropriate.

Definition in file MatrixSolves_lapack.cpp.

Function Documentation

main()

int main

(

)

Definition at line 24 of file MatrixSolves_lapack.cpp.

{
 
  cout << "\n";
  cout << "=== Matrix: Example linear solver  ==================\n";
  cout << "\n";
 
  bool failed = false;
  // tolerance for the test
  const double tol = 1.e-10;
 
  //
  // SOLVE A SMALL "Dense"(!) 2X2 REAL SYSTEM with LAPACK or native
  //
  DenseMatrix<double> A( 2, 2, 0.0 );
  DenseVector<double> B( 2, 0.0 );
  A( 0, 0 ) = 1.;
  A( 0, 1 ) = 2.;
  A( 1, 0 ) = 3.;
  A( 1, 1 ) = 4.;
  B[ 0 ] = 5.;
  B[ 1 ] = 11.;
 
  std::cout << "     Simple 2x2 system solved by LAPACK LU.\n";
  DenseLinearSystem<double> small_system( &A, &B, "lapack" );
 
  try
  {
    small_system.solve();
  }
  catch (const std::runtime_error &error )
  {
    cout << " \033[1;31;48m  * FAILED THROUGH EXCEPTION BEING RAISED \033[0m\n";
    return 1;
  }
  DenseVector<double> answer( 2, 0.0 );
  answer[ 0 ] = 1.0;
  answer[ 1 ] = 2.0;
  B.sub( answer );
  if ( B.inf_norm() > tol )
  {
    std::cout << " Simple 2x2 system was not solved correctly\n";
    std::cout << " residual vector's inf_norm = " << B.inf_norm() << "\n";
    failed = true;
  }
  else
  {
    std::cout << "     Simple 2x2 `dense' solver works.\n";
  }
 
  //
  // CONCLUDING PASS/FAIL
  //
  if ( failed )
  {
    cout << "\033[1;31;48m  * FAILED \033[0m\n";
    return 1;
  }
  else
  {
    cout << "\033[1;32;48m  * PASSED \033[0m\n";
    return 0;
  }
}

References CppNoddy::DenseVector< _Type >::inf_norm(), CppNoddy::DenseLinearSystem< _Type >::solve(), and CppNoddy::DenseVector< _Type >::sub().