fallback_matrix_methods.hpp

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// Emacs Mode Line: -*- Mode:c++;-*-
// -------------------------------------------------------------
/*
 *     Copyright (c) 2013 Battelle Memorial Institute
 *     Licensed under modified BSD License. A copy of this license can be found
 *     in the LICENSE file in the top level directory of this distribution.
 */
// -------------------------------------------------------------
// -------------------------------------------------------------
/**
 * @file   fall_back_matrix_methods.hpp
 * @author William A. Perkins
 * @date   2015-06-02 14:40:24 d3g096
 * 
 * @brief  
 * 
 * 
 */
// -------------------------------------------------------------

#ifndef _fall_back_matrix_methods_hpp_
#define _fall_back_matrix_methods_hpp_

#include "gridpack/parallel/communicator.hpp"
#include "matrix_interface.hpp"
#include "complex_operators.hpp"

namespace gridpack {
namespace math {
namespace fallback {

/// Shift the diagonal of this matrix by the specified value
/** 
 * @c Collective.
 * 
 * @param x 
 */
template <typename T, typename I>
void 
addDiagonal(BaseMatrixInterface<T, I>& A, const T& x)
{
  I lo, hi;
  A.localRowRange(lo, hi);
  for (I i = lo; i < hi; ++i) {
    A.addElement(i, i, x);
  }
  A.ready();
}



template <typename T, typename I>
double 
norm2(const parallel::Communicator& comm, const BaseMatrixInterface<T, I>& A)
{
  I ncols(A.cols());
  I lo, hi;
  A.localRowRange(lo, hi);
  struct l2_norm<T> accum;

  T v;
  for (I i = lo; i < hi; ++i) {
    for (I j = 0; j < ncols; ++j) {
      A.getElement(i, j, v);
      accum(v);
    }
  }
  double lresult(accum.result());
  double result;
  boost::mpi::all_reduce(comm, lresult, result, std::plus<double>());
  result = sqrt(result);
  return result;
}

} // namespace fallback
} // namespace math
} // namespace gridpack


#endif

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