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also allow to add an offset.

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This commit is contained in:
suter_a 2019-10-24 13:02:34 +02:00
parent 2650c7d12b
commit 503336e685
1 changed files with 60 additions and 51 deletions
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111
src/tests/fftw3_bare/fftw3_test.cpp
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@ -4,62 +4,71 @@
#include <fftw3.h> #include <fftw3.h>
void fftw3_test_syntax() { void fftw3_test_syntax() {
std::cout << "fftw3_test [N]" << std::endl; std::cout << std::endl;
std::cout << "fftw3_test [N [offset]]" << std::endl;
std::cout << " N: 2^N Fourier Power" << std::endl; std::cout << " N: 2^N Fourier Power" << std::endl;
std::cout << " default value if not given: N=13 (2^13 = 8192)" << std::endl; std::cout << " default value if not given: N=13 (2^13 = 8192)" << std::endl;
std::cout << " offset: allows to have a length != 2^N, namely 2^N + offset" << std::endl;
std::cout << " default value of offset if not given is 0." << std::endl;
std::cout << std::endl;
} }
int main(int argc, char *argv[]) { int main(int argc, char *argv[]) {
unsigned int N=8192; unsigned int N=8192;
unsigned int offset=0;
if (argc > 2) {
fftw3_test_syntax(); if (argc > 3) {
return 1; fftw3_test_syntax();
} return 1;
}
if (argc == 2) {
int a = -1.0;
int status = sscanf(argv[1], "%d", &a);
if (status != 1) {
fftw3_test_syntax();
return 2;
}
N = (int)pow(2.0, a);
}
std::cout << "debug> N=" << N << std::endl;
fftw_complex *in, *out;
fftw_plan my_plan;
in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
// feed input
double x=0.0;
for (unsigned int i=0; i<N; i++) {
x = (double)i / (double)N;
in[i][0] = sin(100.0*x)*exp(-x/8.0);
in[i][1] = 0.0;
//as35 if ((i%100)==0) std::cout << i << ": x=" << x << ", in=" << in[i][0] << std::endl;
}
my_plan = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(my_plan);
double sumRe = 0.0, sumIm = 0.0;
for (unsigned int i=0; i<N/2; i++) {
//as35 if ((i % 10) == 0) std::cout << i << ": re=" << out[i][0] << ", im=" << out[i][1] << std::endl;
sumRe += out[i][0];
sumIm += out[i][1];
}
std::cout << "sumRe=" << sumRe << std::endl;
std::cout << "sumIm=" << sumIm << std::endl;
fftw_destroy_plan(my_plan); int a=-1;
fftw_free(in); for (int i=1; i<argc; i++) {
fftw_free(out); int status = sscanf(argv[i], "%d", &a);
if (status != 1) {
fftw3_test_syntax();
return 2;
}
if (i==1) // N
N = (unsigned int)pow(2.0, a);
if (i==2) // offset
offset = (unsigned int)a;
}
std::cout << "debug> N=" << N << ", offset=" << offset << std::endl;
return 0; fftw_complex *in, *out;
fftw_plan my_plan;
N += offset;
in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
// feed input
double x=0.0;
for (unsigned int i=0; i<N; i++) {
x = (double)i / (double)N;
in[i][0] = sin(100.0*x)*exp(-x/8.0);
in[i][1] = 0.0;
//as35 if ((i%100)==0) std::cout << i << ": x=" << x << ", in=" << in[i][0] << std::endl;
}
my_plan = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(my_plan);
double sumRe = 0.0, sumIm = 0.0;
for (unsigned int i=0; i<N/2; i++) {
//as35 if ((i % 10) == 0) std::cout << i << ": re=" << out[i][0] << ", im=" << out[i][1] << std::endl;
sumRe += out[i][0];
sumIm += out[i][1];
}
std::cout << "sumRe=" << sumRe << std::endl;
std::cout << "sumIm=" << sumIm << std::endl;
fftw_destroy_plan(my_plan);
fftw_free(in);
fftw_free(out);
return 0;
} }