52 lines
1,008 B
C++
52 lines
1,008 B
C++
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#include <fftw3.h>
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#include <cmath>
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#include <libplotcpp/plotcpp.hpp>
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double pi() {
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return 3.1415;
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}
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std::vector<double> tfd2vect(fftw_complex* tfd, int N) {
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std::vector<double> res;
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auto it = tfd;
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for (int i = 0; i != N; ++i) {
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fftw_complex c = {*it[0], *it[1]};
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res.push_back(sqrt(c[0]*c[0] + c[1]*c[1]));
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it++;
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}
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return res;
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}
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int main(int argc, char** argv) {
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QApplication app(argc, argv);
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fftw_complex *in, *out;
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fftw_plan p;
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int N = 500;
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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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p = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_MEASURE);
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std::vector<double> xx;
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for (int i = 0; i != N; ++i) {
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xx.push_back(i);
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}
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for (int i = 0; i != N; ++i) {
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in[i][0] = sin(2*pi()*50*i/N);
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}
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fftw_execute(p); /* repeat as needed */
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std::vector<double> res = tfd2vect(out, N);
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PlotCpp g;
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g.plot(xx, res);
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g.draw();
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fftw_destroy_plan(p);
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fftw_free(in); fftw_free(out);
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return app.exec();
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}
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