void init_fcs(void) {
FCSResult res;
fcs_int srf = 1;
char *method;
fcs_int pbc [3] = { pbc_dirs.x, pbc_dirs.y, pbc_dirs.z };
fcs_float BoxX[3] = { box_x.x, box_x.y, box_x.z };
fcs_float BoxY[3] = { box_y.x, box_y.y, box_y.z };
fcs_float BoxZ[3] = { box_z.x, box_z.y, box_z.z };
fcs_float off [3] = { 0.0, 0.0, 0.0 };
/* subtract CM momentum */
if (0 == imdrestart) {
int i, k; real ptot[4], ptot_2[4], px, py, pz;
ptot[0] = 0.0; ptot[1] = 0.0; ptot[2] = 0.0, ptot[3] = 0.0;
for (k=0; k<NCELLS; ++k) { /* loop over all cells */
cell *p = CELLPTR(k);
for (i=0; i<p->n; i++) {
ptot[0] += IMPULS(p,i,X);
ptot[1] += IMPULS(p,i,Y);
ptot[2] += IMPULS(p,i,Z);
ptot[3] += MASSE(p,i);
}
}
#ifdef MPI
MPI_Allreduce( ptot, ptot_2, 4, REAL, MPI_SUM, cpugrid);
ptot[0] = ptot_2[0];
ptot[1] = ptot_2[1];
ptot[2] = ptot_2[2];
ptot[3] = ptot_2[3];
#endif
px = ptot[0]/ptot[3];
py = ptot[1]/ptot[3];
pz = ptot[2]/ptot[3];
for (k=0; k<NCELLS; ++k) { /* loop over all cells */
cell *p = CELLPTR(k);
for (i=0; i<p->n; i++) {
IMPULS(p,i,X) -= px * MASSE(p,i);
IMPULS(p,i,Y) -= py * MASSE(p,i);
IMPULS(p,i,Z) -= pz * MASSE(p,i);
}
}
}
switch (fcs_method) {
case FCS_METH_DIRECT: method = "direct"; break;
case FCS_METH_PEPC: method = "pepc"; break;
case FCS_METH_FMM: method = "fmm"; break;
case FCS_METH_P3M: method = "p3m"; srf = fcs_near_field_flag; break;
case FCS_METH_P2NFFT: method = "p2nfft"; srf = fcs_near_field_flag; break;
case FCS_METH_VMG: method = "vmg"; break;
case FCS_METH_PP3MG: method = "pp3mg"; break;
}
/* initialize handle and set common parameters */
res = fcs_init(&handle, method, cpugrid);
ASSERT_FCS(res);
res = fcs_set_common(handle, srf, BoxX, BoxY, BoxZ, off, pbc, natoms);
ASSERT_FCS(res);
res = fcs_require_virial(handle, 1);
ASSERT_FCS(res);
/* set method specific parameters */
switch (fcs_method) {
#ifdef FCS_ENABLE_DIRECT
case FCS_METH_DIRECT:
/* nothing to do */
break;
#endif
#ifdef FCS_ENABLE_PEPC
case FCS_METH_PEPC:
res = fcs_pepc_setup(handle, (fcs_float)fcs_pepc_eps,
(fcs_float)fcs_pepc_theta );
ASSERT_FCS(res);
res = fcs_pepc_set_num_walk_threads( handle, (fcs_int)fcs_pepc_nthreads );
ASSERT_FCS(res);
break;
#endif
#ifdef FCS_ENABLE_FMM
case FCS_METH_FMM:
res = fcs_fmm_set_absrel(handle, (fcs_int)fcs_fmm_absrel);
ASSERT_FCS(res);
res = fcs_fmm_set_tolerance_energy(handle, (fcs_float)fcs_tolerance);
ASSERT_FCS(res);
break;
#endif
#ifdef FCS_ENABLE_P3M
case FCS_METH_P3M:
if (0==srf) {
res = fcs_p3m_set_r_cut(handle, (fcs_float)fcs_rcut);
ASSERT_FCS(res);
}
res = fcs_set_tolerance(handle, FCS_TOLERANCE_TYPE_FIELD,
(fcs_float)fcs_tolerance);
ASSERT_FCS(res);
if (fcs_grid_dim.x)
res = fcs_p3m_set_grid(handle, (fcs_int)fcs_grid_dim.x);
ASSERT_FCS(res);
break;
#endif
#ifdef FCS_ENABLE_P2NFFT
case FCS_METH_P2NFFT:
if (0==srf) {
res = fcs_p2nfft_set_r_cut(handle, (fcs_float)fcs_rcut);
ASSERT_FCS(res);
}
res = fcs_set_tolerance(handle, FCS_TOLERANCE_TYPE_FIELD,
(fcs_float)fcs_tolerance);
ASSERT_FCS(res);
if (fcs_grid_dim.x) {
res = fcs_p2nfft_set_grid(handle, (fcs_int)fcs_grid_dim.x,
(fcs_int)fcs_grid_dim.y, (fcs_int)fcs_grid_dim.z);
ASSERT_FCS(res);
}
if (fcs_p2nfft_intpol_order) {
res = fcs_p2nfft_set_pnfft_interpolation_order(handle,
(fcs_int)fcs_p2nfft_intpol_order);
ASSERT_FCS(res);
}
if (fcs_p2nfft_epsI) {
res = fcs_p2nfft_set_epsI(handle, (fcs_float)fcs_p2nfft_epsI);
ASSERT_FCS(res);
}
//res = fcs_p2nfft_set_pnfft_window_by_name(handle, "bspline");
//ASSERT_FCS(res);
break;
#endif
#ifdef FCS_ENABLE_VMG
case FCS_METH_VMG:
if (fcs_vmg_near_field_cells) {
res = fcs_vmg_set_near_field_cells(handle, (fcs_int)fcs_vmg_near_field_cells);
ASSERT_FCS(res);
}
if (fcs_vmg_interpol_order) {
res = fcs_vmg_set_interpolation_order(handle, (fcs_int)fcs_vmg_interpol_order);
ASSERT_FCS(res);
}
if (fcs_vmg_discr_order) {
res = fcs_vmg_set_discretization_order(handle, (fcs_int)fcs_vmg_discr_order);
ASSERT_FCS(res);
}
if (fcs_iter_tolerance > 0) {
res = fcs_vmg_set_precision(handle, (fcs_float)fcs_iter_tolerance);
ASSERT_FCS(res);
}
break;
#endif
#ifdef FCS_ENABLE_PP3MG
case FCS_METH_PP3MG:
/* use default values, if not specified otherwise */
if (fcs_grid_dim.x) {
res = fcs_pp3mg_set_cells_x(handle, (fcs_int)fcs_grid_dim.x);
ASSERT_FCS(res);
res = fcs_pp3mg_set_cells_y(handle, (fcs_int)fcs_grid_dim.y);
ASSERT_FCS(res);
res = fcs_pp3mg_set_cells_z(handle, (fcs_int)fcs_grid_dim.z);
ASSERT_FCS(res);
}
if (fcs_pp3mg_ghosts) {
res = fcs_pp3mg_set_ghosts(handle, (fcs_int)fcs_pp3mg_ghosts);
ASSERT_FCS(res);
}
if (fcs_pp3mg_degree) {
res = fcs_pp3mg_set_degree(handle, (fcs_int)fcs_pp3mg_degree);
ASSERT_FCS(res);
}
if (fcs_pp3mg_max_part) {
res = fcs_pp3mg_set_max_particles(handle, (fcs_int)fcs_pp3mg_max_part);
ASSERT_FCS(res);
}
if (fcs_max_iter) {
res = fcs_pp3mg_set_max_iterations(handle,(fcs_int)fcs_max_iter);
ASSERT_FCS(res);
}
if (fcs_iter_tolerance > 0) {
res = fcs_pp3mg_set_tol(handle, (fcs_float)fcs_iter_tolerance);
ASSERT_FCS(res);
}
break;
#endif
default:
error("FCS method unknown or not implemented");
break;
}
pack_fcs();
res = fcs_tune(handle, nloc, nloc_max, pos, chg);
ASSERT_FCS(res);
/* inform about tuned parameters */
switch (fcs_method) {
fcs_int grid_dim[3];
fcs_float r_cut;
#ifdef FCS_ENABLE_P3M
case FCS_METH_P3M:
res = fcs_p3m_get_r_cut(handle, &r_cut);
ASSERT_FCS(res);
res = fcs_p3m_get_grid(handle, grid_dim);
ASSERT_FCS(res);
if (0==myid)
printf("FCS: Tuned grid dimensions, cutoff: %d %d %d, %f\n",
grid_dim[0], grid_dim[1], grid_dim[2], r_cut);
break;
#endif
#ifdef FCS_ENABLE_P2NFFT
case FCS_METH_P2NFFT:
res = fcs_p2nfft_get_grid(handle, grid_dim, grid_dim+1, grid_dim+2);
ASSERT_FCS(res);
res = fcs_p2nfft_get_r_cut(handle, &r_cut);
ASSERT_FCS(res);
if (0==myid)
printf("FCS: Tuned grid dimensions, cutoff: %d %d %d, %f\n",
grid_dim[0], grid_dim[1], grid_dim[2], r_cut);
break;
#endif
#ifdef FCS_ENABLE_PP3MG
case FCS_METH_PP3MG:
res = fcs_pp3mg_get_cells_x(handle, grid_dim );
ASSERT_FCS(res);
res = fcs_pp3mg_get_cells_y(handle, grid_dim+1);
ASSERT_FCS(res);
res = fcs_pp3mg_get_cells_z(handle, grid_dim+2);
if (0==myid)
printf("FCS: Tuned grid dimensions: %d %d %d\n",
grid_dim[0], grid_dim[1], grid_dim[2]);
ASSERT_FCS(res);
break;
#endif
default:
break;
}
/* add near-field potential, after fcs_tune */
if (0==srf) fcs_update_pottab();
}
int scafacos_p3m_tuning(){
int mesh[3] = {0, 0, 0}, tmp_mesh_points;
int tmp_mesh[3];
double r_cut_iL_min, r_cut_iL_max, r_cut_iL = -1, tmp_r_cut_iL=0.0;
int cao;
double alpha_L = -1, tmp_alpha_L=0.0;
double accuracy = -1, tmp_accuracy=0.0;
double time_best=1e20, tmp_time;
char b[3*ES_INTEGER_SPACE + 3*ES_DOUBLE_SPACE + 128];
int buffer_cao, buffer_grid;
double buffer_alpha_L, buffer_r_cut_iL, buffer_tolerance_field;
if (skin == -1) {
// *log = strcat_alloc(*log, "p3m cannot be tuned, since the skin is not yet set");
return ES_ERROR;
}
/* preparation */
mpi_bcast_event(FCS_P3M_COUNT_CHARGES);
/* Print Status */
sprintf(b, "P3M tune parameters: Accuracy goal = %.5e\n", scafacos_p3m.params.tolerance_field);
// *log = strcat_alloc(*log, b);
sprintf(b, "System: box_l = %.5e # charged part = %d Sum[q_i^2] = %.5e\n", box_l[0], scafacos_p3m.sum_qpart, scafacos_p3m.sum_q2);
// *log = strcat_alloc(*log, b);
if (scafacos_p3m.sum_qpart == 0) {
// *log = strcat_alloc(*log, "no charged particles in the system, cannot tune P3M");
return ES_ERROR;
}
double density, r_cut;
density = n_total_particles /(box_l[0]* box_l[1]* box_l[2]);
int number = 100;
r_cut= pow(number/ density/3.14 *3 /4 , 1/3.0);
if(scafacos_p3m.params.r_cut_iL == 0.0) {
// WARNING: r_cut_iL_min should not be small !
r_cut_iL_min = dmin(min_local_box_l, min_box_l/2);
r_cut_iL_min *= 0.18;
r_cut_iL_min = r_cut *0.8;
r_cut_iL_max = dmin(min_local_box_l, min_box_l/2);
r_cut_iL_max *= 0.28;
r_cut_iL_max = r_cut *1.5;
if(r_cut_iL_max >= 4.5)
r_cut_iL_max = 4.5;
// r_cut_iL_max = dmin(min_local_box_l, min_box_l/2);// - skin;
// r_cut_iL_min *= box_l_i[0];
// r_cut_iL_max *= box_l_i[0];
fprintf(stderr, "r_cut_iL_max: %f r_cut_iL_min: %f \n", r_cut_iL_max, r_cut_iL_min);
fprintf(stderr, "box_l is: %f \n", box_l[0]);
}
else{
fprintf(stderr, "Scafacos_p3m tuning varies the cutoff radius; you have to leave cutoff unspecified");
return ES_ERROR;
}
// *log = strcat_alloc(*log, "mesh cao r_cut_iL alpha_L err rs_err ks_err time [ms]\n");
for(tmp_r_cut_iL = r_cut_iL_min; tmp_r_cut_iL <= r_cut_iL_max; tmp_r_cut_iL += 0.1){
scafacos_p3m.params.cutoff = tmp_r_cut_iL;
tmp_time = time_force_calc(1);
// *log = strcat_alloc(*log, " %f ms ");
fprintf(stderr, "time: %f \n", tmp_time);
// *log = strcat_alloc(*log, b);
if ((tmp_time < time_best) && (tmp_time > 0)) {
time_best = tmp_time;
fcs_p3m_get_grid(fcs_handle, &buffer_grid);
fcs_p3m_get_cao(fcs_handle, &buffer_cao);
fcs_p3m_get_r_cut(fcs_handle, &buffer_r_cut_iL);
fcs_p3m_get_alpha(fcs_handle, &buffer_alpha_L);
fcs_p3m_get_tolerance_field(fcs_handle, &buffer_tolerance_field);
// target accuracy remains the same
}
/* no hope of further optimisation */
//else if (tmp_time > time_best + P3M_TIME_GRAN) {
// break;
//}
}
if(time_best == 1e20) {
fprintf(stderr, "failed to tune P3M parameters to required accuracy\n");
return ES_ERROR;
}
/* prepare tuned p3m parameters for broadcast*/
scafacos_p3m.params.cao = buffer_cao;
scafacos_p3m.params.alpha_L = buffer_alpha_L;
scafacos_p3m.params.grid = buffer_grid;
scafacos_p3m.params.cutoff = buffer_r_cut_iL;
scafacos_p3m.params.alpha_L = buffer_alpha_L;
/* Tell the user about the outcome */
fprintf(stderr, "\nresulting parameters:\n%-4d %-3d %.5e %.5e %.5e %-8d\n", buffer_grid, buffer_cao, buffer_r_cut_iL, buffer_alpha_L, buffer_tolerance_field, (int)time_best);
return ES_OK;
}