Added example for LambdaMatrix::forRows.

   LambdaMatrixExample_allRowsReduction

   LambdaMatrixExample_forElements

   LambdaMatrixExample_forAllElements

   #LambdaMatrixExample_forRows

   LambdaMatrixExample_forRows

)

if( BUILD_CUDA )

#include <iostream>

#include <TNL/Matrices/LambdaMatrix.h>

#include <TNL/Matrices/DenseMatrix.h>

#include <TNL/Devices/Host.h>

#include <TNL/Devices/Cuda.h>

template< typename Device >

void forRowsExample()

{

   /**

    * Prepare lambda matrix of the following form:

    *

    * /  1   0   0   0   0 \

    * | -2   1  -2   0   0 |

    * |  0  -2   1  -2   0 |

    * |  0   0  -2   1  -2 |

    * |  0   0   0  -2   1 |

    * \  0   0   0   0   1 /

    */

   int size = 5;

   auto rowLengths = [=] __cuda_callable__ ( const int rows, const int columns, const int rowIdx ) -> int {

      if( rowIdx == 0 || rowIdx == size - 1 )

         return 1;

      return 3;

   };

   auto matrixElements = [=] __cuda_callable__ ( const int rows, const int columns, const int rowIdx, const int localIdx, int& columnIdx, double& value ) {

      if( rowIdx == 0 || rowIdx == size -1 )

      {

         columnIdx = rowIdx;

         value =  1.0;

      }

      else

      {

         columnIdx = rowIdx + localIdx - 1;

         value = ( columnIdx == rowIdx ) ? -2.0 : 1.0;

      }

   };

   using MatrixType = decltype( TNL::Matrices::LambdaMatrixFactory< double, Device, int >::create( matrixElements, rowLengths ) );

   MatrixType matrix( size, size, matrixElements, rowLengths );

   /**

    * Use the `forRows` method to copy the matrix elements to a dense matrix.

    */

   TNL::Matrices::DenseMatrix< double, Device, int > denseMatrix( size, size );

   denseMatrix.setValue( 0.0 );

   auto dense_view = denseMatrix.getView();

   auto f = [=] __cuda_callable__ ( const typename MatrixType::RowViewType& row ) mutable {

      auto dense_row = dense_view.getRow( row.getRowIndex() );

      for( int localIdx = 0; localIdx < row.getSize(); localIdx++ )

         dense_row.setElement( row.getColumnIndex( localIdx ), row.getValue( localIdx ) );

   };

   matrix.forAllRows( f );

   std::cout << "Lambda matrix looks as:" << std::endl << matrix << std::endl;

   std::cout << "Dense matrix looks as:" << std::endl << denseMatrix << std::endl;

}

int main( int argc, char* argv[] )

{

   std::cout << "Running example on CPU ... " << std::endl;

   forRowsExample< TNL::Devices::Host >();

#ifdef HAVE_CUDA

   std::cout << "Running example on CUDA GPU ... " << std::endl;

   forRowsExample< TNL::Devices::Cuda >();

#endif

}

LambdaMatrixExample_forRows.cpp

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