Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F102270956
min_cg.cpp
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Tue, Feb 18, 23:25
Size
5 KB
Mime Type
text/x-c
Expires
Thu, Feb 20, 23:25 (2 d)
Engine
blob
Format
Raw Data
Handle
24320855
Attached To
rLAMMPS lammps
min_cg.cpp
View Options
/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include <mpi.h>
#include <math.h>
#include <string.h>
#include "min_cg.h"
#include "atom.h"
#include "update.h"
#include "output.h"
#include "timer.h"
using namespace LAMMPS_NS;
// EPS_ENERGY = minimum normalization for energy tolerance
#define EPS_ENERGY 1.0e-8
// same as in other min classes
enum{MAXITER,MAXEVAL,ETOL,FTOL,DOWNHILL,ZEROALPHA,ZEROFORCE,ZEROQUAD};
/* ---------------------------------------------------------------------- */
MinCG::MinCG(LAMMPS *lmp) : MinLineSearch(lmp) {}
/* ----------------------------------------------------------------------
minimization via conjugate gradient iterations
------------------------------------------------------------------------- */
int MinCG::iterate(int maxiter)
{
int i,m,n,fail,ntimestep;
double beta,gg,dot[2],dotall[2];
double *fatom,*gatom,*hatom;
// nlimit = max # of CG iterations before restarting
// set to ndoftotal unless too big
int nlimit = static_cast<int> (MIN(MAXSMALLINT,ndoftotal));
// initialize working vectors
for (i = 0; i < nvec; i++) h[i] = g[i] = fvec[i];
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
fatom = fextra_atom[m];
gatom = gextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) hatom[i] = gatom[i] = fatom[i];
}
if (nextra_global)
for (i = 0; i < nextra_global; i++) hextra[i] = gextra[i] = fextra[i];
gg = fnorm_sqr();
for (int iter = 0; iter < maxiter; iter++) {
ntimestep = ++update->ntimestep;
niter++;
// line minimization along direction h from current atom->x
eprevious = ecurrent;
fail = (this->*linemin)(ecurrent,alpha_final);
if (fail) return fail;
// function evaluation criterion
if (neval >= update->max_eval) return MAXEVAL;
// energy tolerance criterion
if (fabs(ecurrent-eprevious) <
update->etol * 0.5*(fabs(ecurrent) + fabs(eprevious) + EPS_ENERGY))
return ETOL;
// force tolerance criterion
dot[0] = dot[1] = 0.0;
for (i = 0; i < nvec; i++) {
dot[0] += fvec[i]*fvec[i];
dot[1] += fvec[i]*g[i];
}
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
fatom = fextra_atom[m];
gatom = gextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) {
dot[0] += fatom[i]*fatom[i];
dot[1] += fatom[i]*gatom[i];
}
}
MPI_Allreduce(dot,dotall,2,MPI_DOUBLE,MPI_SUM,world);
if (nextra_global)
for (i = 0; i < nextra_global; i++) {
dotall[0] += fextra[i]*fextra[i];
dotall[1] += fextra[i]*gextra[i];
}
if (dotall[0] < update->ftol*update->ftol) return FTOL;
// update new search direction h from new f = -Grad(x) and old g
// this is Polak-Ribieri formulation
// beta = dotall[0]/gg would be Fletcher-Reeves
// reinitialize CG every ndof iterations by setting beta = 0.0
beta = MAX(0.0,(dotall[0] - dotall[1])/gg);
if ((niter+1) % nlimit == 0) beta = 0.0;
gg = dotall[0];
for (i = 0; i < nvec; i++) {
g[i] = fvec[i];
h[i] = g[i] + beta*h[i];
}
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
fatom = fextra_atom[m];
gatom = gextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) {
gatom[i] = fatom[i];
hatom[i] = gatom[i] + beta*hatom[i];
}
}
if (nextra_global)
for (i = 0; i < nextra_global; i++) {
gextra[i] = fextra[i];
hextra[i] = gextra[i] + beta*hextra[i];
}
// reinitialize CG if new search direction h is not downhill
dot[0] = 0.0;
for (i = 0; i < nvec; i++) dot[0] += g[i]*h[i];
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
gatom = gextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) dot[0] += gatom[i]*hatom[i];
}
MPI_Allreduce(dot,dotall,1,MPI_DOUBLE,MPI_SUM,world);
if (nextra_global)
for (i = 0; i < nextra_global; i++)
dotall[0] += gextra[i]*hextra[i];
if (dotall[0] <= 0.0) {
for (i = 0; i < nvec; i++) h[i] = g[i];
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
gatom = gextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) hatom[i] = gatom[i];
}
if (nextra_global)
for (i = 0; i < nextra_global; i++) hextra[i] = gextra[i];
}
// output for thermo, dump, restart files
if (output->next == ntimestep) {
timer->stamp();
output->write(ntimestep);
timer->stamp(Timer::OUTPUT);
}
}
return MAXITER;
}
Event Timeline
Log In to Comment