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/* Copyright (C) 2005-2022 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
*/
/* Nonlinear test program checking 2nd and 3rd harmonic generation */
#include <meep.hpp>
using namespace meep;
using std::max;
double the_value = 1.0;
double value(const vec &) { return the_value; }
void harmonics(double freq, double chi2, double chi3, double J, double &A2, double &A3) {
const double dpml = 5.0;
const double res = 20;
const double sz = 100 + 2 * dpml;
grid_volume gv = vol1d(sz, res);
gv.center_origin();
the_value = 1.0;
structure s(gv, value, pml(dpml));
the_value = chi2;
s.set_chi2(value);
the_value = chi3;
s.set_chi3(value);
fields f(&s);
f.use_real_fields();
gaussian_src_time src(freq, freq / 20);
f.add_point_source(Ex, src, vec(-0.5 * sz + dpml), J);
vec fpt(0.5 * sz - dpml - 0.5);
dft_flux d1 =
f.add_dft_flux(Z, volume(fpt), freq, freq, 1, true, true, 1 /* decimation_factor */);
dft_flux d2 =
f.add_dft_flux(Z, volume(fpt), 2 * freq, 2 * freq, 1, true, true, 1 /* decimation_factor */);
dft_flux d3 =
f.add_dft_flux(Z, volume(fpt), 3 * freq, 3 * freq, 1, true, true, 1 /* decimation_factor */);
double emax = 0;
while (f.time() < f.last_source_time()) {
emax = max(emax, abs(f.get_field(Ex, fpt)));
f.step();
}
do {
double emaxcur = 0;
double T = f.time() + 50;
while (f.time() < T) {
double e = abs(f.get_field(Ex, fpt));
emax = max(emax, e);
emaxcur = max(emaxcur, e);
f.step();
}
if (emaxcur < 1e-6 * emax) break;
} while (1);
double *d1f = d1.flux();
double *d2f = d2.flux();
double *d3f = d3.flux();
A2 = *d2f / *d1f;
A3 = *d3f / *d1f;
master_printf("harmonics(%g,%g,%g) = %g, %g\n", chi2, chi3, J, A2, A3);
delete[] d1f;
delete[] d2f;
delete[] d3f;
}
int different(double a, double a0, double thresh, const char *msg) {
if (fabs(a - a0) > thresh * fabs(a0)) {
master_printf("error: %s\n --- %g vs. %g (%g error > %g)\n", msg, a, a0,
fabs(a - a0) / fabs(a0), thresh);
return 1;
}
else
return 0;
}
int main(int argc, char **argv) {
initialize mpi(argc, argv);
verbosity = 0;
const double freq = 1.0 / 3.0;
double a2, a3, a2_2, a3_2;
double thresh = sizeof(realnum) == sizeof(float) ? 1e-3 : 1e-5;
harmonics(freq, 0.27e-4, 1e-4, 1.0, a2, a3);
if (different(a2, 9.80330e-07, thresh, "2nd harmonic mismatches known val")) return 1;
if (sizeof(realnum) == sizeof(float)) {
if (different(a3, 9.99349e-07, thresh, "3rd harmonic mismatches known val")) return 1;
}
else {
if (different(a3, 9.97747e-07, thresh, "3rd harmonic mismatches known val")) return 1;
}
harmonics(freq, 0.54e-4, 2e-4, 1.0, a2_2, a3_2);
master_printf("doubling chi2, chi3 = %g x 2nd harmonic, %g x 3rd\n", a2_2 / a2, a3_2 / a3);
if (different(a2_2 / a2, 4.0, 0.01, "incorrect chi2 scaling")) return 1;
if (different(a3_2 / a3, 4.0, 0.01, "incorrect chi3 scaling")) return 1;
harmonics(freq, 0.27e-4, 1e-4, 2.0, a2_2, a3_2);
master_printf("doubling J = %g x 2nd harmonic, %g x 3rd\n", a2_2 / a2, a3_2 / a3);
if (different(a2_2 / a2, 4.0, 0.01, "incorrect J scaling for 2nd harm.")) return 1;
if (different(a3_2 / a3, 16.0, 0.01, "incorrect J scaling for 3rd harm.")) return 1;
harmonics(freq, 0.27e-4, 0.0, 1.0, a2_2, a3_2);
if (different(a2, a2_2, 1e-2, "chi3 has too big effect on 2nd harmonic")) return 1;
if (a3_2 / a3 > 1e-4) {
master_printf("error: too much 3rd harmonic without chi3\n");
return 1;
}
harmonics(freq, 0.0, 1e-4, 1.0, a2_2, a3_2);
if (sizeof(realnum) == sizeof(float)) {
if (different(a3, a3_2, 0.0017, "chi2 has too big effect on 3rd harmonic")) return 1;
}
else {
if (different(a3, a3_2, 0.001, "chi2 has too big effect on 3rd harmonic")) return 1;
}
if (a2_2 / a2 > 1e-5) {
master_printf("error: too much 2nd harmonic without chi3\n");
return 1;
}
return 0;
}
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