/usr/include/trilinos/Stokhos_Tpetra_CG.hpp is in libtrilinos-stokhos-dev 12.10.1-3.
This file is owned by root:root, with mode 0o644.
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// ***********************************************************************
//
// Stokhos Package
// Copyright (2009) Sandia Corporation
//
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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// met:
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// 1. Redistributions of source code must retain the above copyright
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// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the Corporation nor the names of the
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// @HEADER
#ifndef STOKHOS_TPETRA_CG_HPP
#define STOKHOS_TPETRA_CG_HPP
namespace Stokhos {
// A simple CG solver for Tpetra-like objects
template <typename Matrix,
typename Vector,
typename Ordinal>
bool CG_Solve(const Matrix& A, Vector& x, const Vector& b,
typename Vector::mag_type tol, Ordinal max_its,
std::ostream* out = 0)
{
typedef typename Vector::mag_type mag_type;
typedef typename Vector::dot_type dot_type;
Vector r(b.getMap());
Vector p(x.getMap());
Vector w(x.getMap());
A.apply(x, r);
r.update(1.0, b, -1.0);
dot_type rho = r.dot(r);
dot_type rho_old = rho;
mag_type nrm = std::sqrt(rho);
Ordinal k=0;
dot_type alpha, beta, pAp;
while (k < max_its && nrm > tol) {
if (k == 0) {
p.update(1.0, r, 0.0);
}
else {
beta = rho / rho_old;
p.update(1.0, r, beta);
}
A.apply(p, w);
pAp = p.dot(w);
alpha = rho/pAp;
x.update( alpha, p, 1.0);
r.update(-alpha, w, 1.0);
rho_old = rho;
rho = r.dot(r);
nrm = std::sqrt(rho);
++k;
if (out)
*out << k << ": " << nrm << std::endl;
}
if (nrm <= tol)
return true;
return false;
}
// A simple preconditioned CG solver based for Tpetra-like objects
template <typename Matrix,
typename Vector,
typename Prec,
typename Ordinal>
bool PCG_Solve(const Matrix& A, Vector& x, const Vector& b, const Prec& M,
typename Vector::mag_type tol, Ordinal max_its,
std::ostream* out = 0)
{
typedef typename Vector::mag_type mag_type;
typedef typename Vector::dot_type dot_type;
Vector r(b.getMap());
Vector p(x.getMap());
Vector w(x.getMap());
A.apply(x, r);
r.update(1.0, b, -1.0);
mag_type nrm = r.norm2();
dot_type rho = 1.0;
Ordinal k=0;
dot_type rho_old, alpha, beta, pAp;
while (k < max_its && nrm > tol) {
M.apply(r, w);
rho_old = rho;
rho = r.dot(w);
if (k == 0) {
p.update(1.0, w, 0.0);
}
else {
beta = rho / rho_old;
p.update(1.0, w, beta);
}
A.apply(p, w);
pAp = p.dot(w);
alpha = rho/pAp;
x.update( alpha, p, 1.0);
r.update(-alpha, w, 1.0);
nrm = r.norm2();
++k;
if (out)
*out << k << ": " << nrm << std::endl;
}
if (nrm <= tol)
return true;
return false;
}
}
#endif // STOKHOS_TPETRA_CG
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