44 lines
1.1 KiB
C++
44 lines
1.1 KiB
C++
#include <iostream>
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#include <cmath>
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#include <fftw3.h>
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int main(int argc, char *argv[]) {
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const unsigned int N=8192;
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fftw_complex *in, *out;
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fftw_plan my_plan;
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in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
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out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*N);
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// feed input
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double x=0.0;
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for (unsigned int i=0; i<N; i++) {
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x = (double)i / (double)N;
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in[i][0] = sin(100.0*x)*exp(-x/8.0);
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in[i][1] = 0.0;
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//as35 if ((i%100)==0) std::cout << i << ": x=" << x << ", in=" << in[i][0] << std::endl;
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}
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my_plan = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
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fftw_execute(my_plan);
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double sumRe = 0.0, sumIm = 0.0;
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for (unsigned int i=0; i<N/2; i++) {
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//as35 if ((i % 10) == 0) std::cout << i << ": re=" << out[i][0] << ", im=" << out[i][1] << std::endl;
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sumRe += out[i][0];
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sumIm += out[i][1];
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}
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std::cout << "sumRe=" << sumRe << std::endl;
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std::cout << "sumIm=" << sumIm << std::endl;
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fftw_destroy_plan(my_plan);
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fftw_free(in);
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fftw_free(out);
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return 0;
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}
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