/
cw_fields.cpp
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/
cw_fields.cpp
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/* Copyright (C) 2005-2020 Massachusetts Institute of Technology.
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "meep_internals.hpp"
#include "bicgstab.hpp"
using namespace std;
namespace meep {
static void fields_to_array(const fields &f, complex<realnum> *x) {
size_t ix = 0;
for (int i = 0; i < f.num_chunks; i++)
if (f.chunks[i]->is_mine()) FOR_COMPONENTS(c) {
if (is_D(c) || is_B(c)) {
realnum *fr, *fi;
#define COPY_FROM_FIELD(fld) \
if ((fr = f.chunks[i]->fld[0]) && (fi = f.chunks[i]->fld[1])) \
LOOP_OVER_VOL_OWNED(f.chunks[i]->gv, c, idx) \
x[ix++] = complex<double>(fr[idx], fi[idx]);
COPY_FROM_FIELD(f[c]);
COPY_FROM_FIELD(f_u[c]);
COPY_FROM_FIELD(f_cond[c]);
component c2 = field_type_component(is_D(c) ? E_stuff : H_stuff, c);
COPY_FROM_FIELD(f_w[c2]);
if (f.chunks[i]->f_w[c2][0]) COPY_FROM_FIELD(f[c2]);
#undef COPY_FROM_FIELD
}
}
}
static void array_to_fields(const complex<realnum> *x, fields &f) {
size_t ix = 0;
for (int i = 0; i < f.num_chunks; i++)
if (f.chunks[i]->is_mine()) FOR_COMPONENTS(c) {
if (is_D(c) || is_B(c)) {
realnum *fr, *fi;
#define COPY_TO_FIELD(fld) \
if ((fr = f.chunks[i]->fld[0]) && (fi = f.chunks[i]->fld[1])) \
LOOP_OVER_VOL_OWNED(f.chunks[i]->gv, c, idx) { \
fr[idx] = real(x[ix]); \
fi[idx] = imag(x[ix++]); \
}
COPY_TO_FIELD(f[c]);
COPY_TO_FIELD(f_u[c]);
COPY_TO_FIELD(f_cond[c]);
component c2 = field_type_component(is_D(c) ? E_stuff : H_stuff, c);
COPY_TO_FIELD(f_w[c2]);
if (f.chunks[i]->f_w[c2][0]) COPY_TO_FIELD(f[c2]);
#undef COPY_TO_FIELD
}
}
f.step_boundaries(D_stuff);
f.update_eh(E_stuff, true);
f.step_boundaries(E_stuff);
/* done in f.step before updating D:
f.step_boundaries(B_stuff);
f.update_eh(H_stuff);
f.step_boundaries(H_stuff); */
}
typedef struct {
size_t n;
fields *f;
complex<double> iomega;
int iters;
} fieldop_data;
static void fieldop(const realnum *xr, realnum *yr, void *data_) {
const complex<realnum> *x = reinterpret_cast<const complex<realnum> *>(xr);
complex<realnum> *y = reinterpret_cast<complex<realnum> *>(yr);
fieldop_data *data = (fieldop_data *)data_;
array_to_fields(x, *data->f);
data->f->step();
fields_to_array(*data->f, y);
size_t n = data->n;
realnum dt_inv = 1.0 / data->f->dt;
complex<realnum> iomega = complex<realnum>(real(data->iomega), imag(data->iomega));
for (size_t i = 0; i < n; ++i)
y[i] = (y[i] - x[i]) * dt_inv + iomega * x[i];
data->iters++;
}
/* Solve for the CW (constant frequency) field response at the given
frequency to the sources (with amplitude given by the current sources
at the current time). The solver halts at a fractional convergence
of tol, or when maxiters is reached, or when convergence fails;
returns true if convergence succeeds and false if it fails.
The parameter L determines the order of the iterative algorithm
that is used. L should always be positive and should normally be
>= 2. Larger values of L will often lead to faster convergence, at
the expense of more memory and more work per iteration. */
bool fields::solve_cw(double tol, int maxiters, complex<double> frequency, int L) {
if (is_real) abort("solve_cw is incompatible with use_real_fields()");
if (L < 1) abort("solve_cw called with L = %d < 1", L);
int tsave = t; // save time (gets incremented by iterations)
set_solve_cw_omega(2 * pi * frequency);
step(); // step once to make sure everything is allocated
size_t N = 0; // size of linear system (on this processor, at least)
for (int i = 0; i < num_chunks; i++)
if (chunks[i]->is_mine()) {
FOR_COMPONENTS(c) {
if (chunks[i]->f[c][0] && (is_D(c) || is_B(c))) {
component c2 = field_type_component(is_D(c) ? E_stuff : H_stuff, c);
/* unknowns are just D and B in non-PML regions, but in PML
regions the E, U, W, and C fields are also unknowns (in
principle, we might be able to compute these extra fields
in frequency domain via scalinb by the appropriate s
factors, rather than storing them, but I had some
problems getting that working) */
N += 2 * chunks[i]->gv.nowned(c) *
(1 + (chunks[i]->f_u[c][0] != NULL) + (chunks[i]->f_w[c2][0] != NULL) * 2 +
(chunks[i]->f_cond[c][0] != NULL));
}
}
}
size_t nwork = (size_t)bicgstabL(L, N, 0, 0, 0, 0, tol, &maxiters, 0, true);
realnum *work = new realnum[nwork + 2 * N];
complex<realnum> *x = reinterpret_cast<complex<realnum> *>(work + nwork);
complex<realnum> *b = reinterpret_cast<complex<realnum> *>(work + nwork + N);
fields_to_array(*this, x); // initial guess = initial fields
// get J amplitudes from current time step
zero_fields(); // note that we've saved the fields in x above
calc_sources(time());
step_source(B_stuff, true);
step_boundaries(B_stuff);
update_eh(H_stuff);
calc_sources(time() + 0.5 * dt);
step_source(D_stuff, true);
step_boundaries(D_stuff);
update_eh(E_stuff);
fields_to_array(*this, b);
double mdt_inv = -1.0 / dt;
for (size_t i = 0; i < N / 2; ++i)
b[i] *= mdt_inv;
{
double bmax = 0;
for (size_t i = 0; i < N / 2; ++i) {
double babs = abs(b[i]);
if (babs > bmax) bmax = babs;
}
if (max_to_all(bmax) == 0.0) abort("zero current amplitudes in solve_cw");
}
fieldop_data data;
data.f = this;
data.n = N / 2;
data.iomega = ((1.0 - exp(complex<double>(0., -1.) * (2 * pi * frequency) * dt)) * (1.0 / dt));
data.iters = 0;
int ierr = (int)bicgstabL(L, N, reinterpret_cast<realnum *>(x), fieldop, &data,
reinterpret_cast<realnum *>(b), tol, &maxiters, work, verbosity == 0);
if (verbosity > 0) {
master_printf("Finished solve_cw after %d steps and %d CG iters.\n", data.iters, maxiters);
if (ierr) master_printf(" -- CONVERGENCE FAILURE (%d) in solve_cw!\n", ierr);
}
array_to_fields(x, *this);
step(); // ensure H/B are updated and synced with E/D
delete[] work;
t = tsave;
unset_solve_cw_omega();
update_dfts();
return !ierr;
}
/* as solve_cw, but infers frequency from sources */
bool fields::solve_cw(double tol, int maxiters, int L) {
complex<double> freq = 0.0;
for (src_time *s = sources; s; s = s->next) {
complex<double> sf = s->frequency();
if (sf != freq && freq != 0.0 && sf != 0.0)
abort("must pass frequency to solve_cw if sources do not agree");
if (sf != 0.0) freq = sf;
}
if (freq == 0.0) abort("must pass frequency to solve_cw if sources do not specify one");
return solve_cw(tol, maxiters, freq, L);
}
} // namespace meep