bool steepest_descent_step(void) {
Cell *cell;
Particle *p;
int c, i, j, np;
double f_max = -std::numeric_limits<double>::max();
double f;
/* Verlet list criterion */
const double skin2 = SQR(0.5*skin);
double f_max_global;
double dx[3], dx2;
const double max_dx2 = SQR(params->max_displacement);
for (c = 0; c < local_cells.n; c++) {
cell = local_cells.cell[c];
p = cell->part;
np = cell->n;
for(i = 0; i < np; i++) {
f = 0.0;
dx2 = 0.0;
#ifdef VIRTUAL_SITES
if (ifParticleIsVirtual(&p[i])) continue;
#endif
for(j=0; j < 3; j++){
#ifdef EXTERNAL_FORCES
if (!(p[i].p.ext_flag & COORD_FIXED(j)))
#endif
{
f += SQR(p[i].f.f[j]);
dx[j] = params->gamma * p[i].f.f[j];
dx2 += SQR(dx[j]);
MINIMIZE_ENERGY_TRACE(printf("part %d dim %d dx %e gamma*f %e\n", i, j, dx[j], params->gamma * p[i].f.f[j]));
}
#ifdef EXTERNAL_FORCES
else {
dx[j] = 0.0;
}
#endif
}
if(dx2 <= max_dx2) {
p[i].r.p[0] += dx[0];
p[i].r.p[1] += dx[1];
p[i].r.p[2] += dx[2];
} else {
const double c = params->max_displacement/std::sqrt(dx2);
p[i].r.p[0] += c*dx[0];
p[i].r.p[1] += c*dx[1];
p[i].r.p[2] += c*dx[2];
}
if(distance2(p[i].r.p,p[i].l.p_old) > skin2 ) resort_particles = 1;
f_max = std::max(f_max, f);
}
}
MINIMIZE_ENERGY_TRACE(printf("f_max %e resort_particles %d\n", f_max, resort_particles));
announce_resort_particles();
MPI_Allreduce(&f_max, &f_max_global, 1, MPI_DOUBLE, MPI_MAX, comm_cart);
return (sqrt(f_max_global) < params->f_max);
}
bool steepest_descent_step(void) {
Cell *cell;
Particle *p;
int c, i, j, np;
// Maximal force encountered on node
double f_max = -std::numeric_limits<double>::max();
// and globally
double f_max_global;
// Square of force,torque on particle
double f,t;
// Positional increments
double dp, dp2, dp2_max = -std::numeric_limits<double>::max();
// Iteration over all local particles
for (c = 0; c < local_cells.n; c++) {
cell = local_cells.cell[c];
p = cell->part;
np = cell->n;
for(i = 0; i < np; i++) {
f = 0.0;
t = 0.0;
dp2 = 0.0;
#ifdef EXTERNAL_FORCES
// Skip, if coordinate is fixed
if (!(p[i].p.ext_flag & COORD_FIXED(j)))
#endif
// For all Cartesian coordinates
for(j=0; j < 3; j++){
#ifdef VIRTUAL_SITES
// Skip positional increments of virtual particles
if (!ifParticleIsVirtual(&p[i]))
#endif
{
// Square of force on particle
f += SQR(p[i].f.f[j]);
// Positional increment
dp = params->gamma * p[i].f.f[j];
if(fabs(dp) > params->max_displacement)
// Crop to maximum allowed by user
dp = sgn<double>(dp)*params->max_displacement;
dp2 += SQR(dp);
// Move particle
p[i].r.p[j] += dp;
MINIMIZE_ENERGY_TRACE(printf("part %d dim %d dp %e gamma*f %e\n", i, j, dp, params->gamma * p[i].f.f[j]));
}
}
#ifdef ROTATION
// Rotational increment
double dq[3]; // Vector parallel to torque
for (int j=0;j<3;j++){
dq[j]=0;
// Square of torque
t += SQR(p[i].f.torque[j]);
// Rotational increment
dq[j] = params->gamma * p[i].f.torque[j];
}
// Normalize rotation axis and compute amount of rotation
double l=normr(dq);
if (l>0.0)
{
for (j=0;j<3;j++)
dq[j]/=l;
if(fabs(l) > params->max_displacement)
// Crop to maximum allowed by user
l=sgn(l)*params->max_displacement;
// printf("dq: %g %g %g, l=%g\n",dq[0],dq[1],dq[2],l);
// Rotate the particle around axis dq by amount l
rotate_particle(&(p[i]),dq,l);
}
#endif
// Note maximum force/torque encountered
f_max = std::max(f_max, f);
f_max = std::max(f_max, t);
dp2_max = std::max(dp2_max, dp2);
resort_particles = 1;
}
}
MINIMIZE_ENERGY_TRACE(printf("f_max %e resort_particles %d\n", f_max, resort_particles));
announce_resort_particles();
// Synchronize maximum force/torque encountered
MPI_Allreduce(&f_max, &f_max_global, 1, MPI_DOUBLE, MPI_MAX, comm_cart);
// Return true, if the maximum force/torque encountered is below the user limit.
return (sqrt(f_max_global) < params->f_max);
}