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new_solver_cg.cc
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rMUSPECTRE µSpectre
new_solver_cg.cc
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/**
* file new_solver_cg.cc
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 24 Apr 2018
*
* @brief implements SolverCGDyn
*
* @section LICENSE
*
* Copyright © 2018 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µSpectre is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "solver/new_solver_cg.hh"
#include "common/communicator.hh"
#include <iomanip>
#include <sstream>
namespace
muSpectre
{
/* ---------------------------------------------------------------------- */
SolverCGDyn
::
SolverCGDyn
(
Cell
&
cell
,
Real
tol
,
Uint
maxiter
,
bool
verbose
)
:
Parent
(
cell
,
tol
,
maxiter
,
verbose
),
r_k
(
cell
.
get_nb_dof
()),
p_k
(
cell
.
get_nb_dof
()),
Ap_k
(
cell
.
get_nb_dof
()),
x_k
(
cell
.
get_nb_dof
())
{}
/* ---------------------------------------------------------------------- */
auto
SolverCGDyn
::
solve
(
const
ConstVector_ref
rhs
)
->
Vector_map
{
this
->
x_k
.
setZero
();
const
Communicator
&
comm
=
this
->
cell
.
get_communicator
();
// Following implementation of algorithm 5.2 in Nocedal's
// Numerical Optimization (p. 112)
//initialisation of algorithm
this
->
r_k
=
(
this
->
cell
.
evaluate_projected_directional_stiffness
(
this
->
x_k
)
-
rhs
);
this
->
p_k
=
-
this
->
r_k
;
this
->
converged
=
false
;
Real
rdr
=
comm
.
sum
(
this
->
r_k
.
dot
(
this
->
r_k
));
Real
rhs_norm2
=
comm
.
sum
(
rhs
.
squaredNorm
());
Real
tol2
=
ipow
(
this
->
tol
,
2
)
*
rhs_norm2
;
size_t
count_width
{};
// for output formatting in verbose case
if
(
this
->
verbose
)
{
count_width
=
size_t
(
std
::
log10
(
this
->
maxiter
))
+
1
;
}
for
(
Uint
i
=
0
;
i
<
this
->
maxiter
&&
(
rdr
>
tol2
||
i
==
0
);
++
i
,
++
this
->
counter
)
{
this
->
Ap_k
=
this
->
cell
.
evaluate_projected_directional_stiffness
(
this
->
p_k
);
Real
alpha
=
rdr
/
comm
.
sum
(
this
->
p_k
.
dot
(
this
->
Ap_k
));
this
->
x_k
+=
alpha
*
this
->
p_k
;
this
->
r_k
+=
alpha
*
this
->
Ap_k
;
Real
new_rdr
=
comm
.
sum
(
this
->
r_k
.
dot
(
this
->
r_k
));
Real
beta
=
new_rdr
/
rdr
;
rdr
=
new_rdr
;
if
(
this
->
verbose
&&
comm
.
rank
()
==
0
)
{
std
::
cout
<<
" at CG step "
<<
std
::
setw
(
count_width
)
<<
i
<<
": |r|/|b| = "
<<
std
::
setw
(
15
)
<<
std
::
sqrt
(
rdr
/
rhs_norm2
)
<<
", cg_tol = "
<<
this
->
tol
<<
std
::
endl
;
}
this
->
p_k
=
-
this
->
r_k
+
beta
*
this
->
p_k
;
}
if
(
rdr
<
tol2
)
{
this
->
converged
=
true
;
}
else
{
std
::
stringstream
err
{};
err
<<
" After "
<<
this
->
counter
<<
" steps, the solver "
<<
" FAILED with |r|/|b| = "
<<
std
::
setw
(
15
)
<<
std
::
sqrt
(
rdr
/
rhs_norm2
)
<<
", cg_tol = "
<<
this
->
tol
<<
std
::
endl
;
throw
ConvergenceError
(
"Conjugate gradient has not converged."
+
err
.
str
());
}
return
Vector_map
(
this
->
x_k
.
data
(),
this
->
x_k
.
size
());
}
}
// muSpectre
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