#include <fftw3.h>
#include <cmath>
#include <libplotcpp/plotcpp.hpp>

double pi() {
	return 3.1415;
}

std::vector<double> tfd2vect(fftw_complex* tfd, int N) {
	std::vector<double> res;
	auto it = tfd;
	for (int i = 0; i != N; ++i) {
		fftw_complex c = {*it[0], *it[1]};
		res.push_back(sqrt(c[0]*c[0] + c[1]*c[1]));
		it++;
	}

	return res;
}

int main(int argc, char** argv) {
	QApplication app(argc, argv);
	fftw_complex *in, *out;
	fftw_plan p;

	int N = 500;
	in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);
	out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);
	p = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_MEASURE);

	std::vector<double> xx;
	for (int i = 0; i != N; ++i) {
		xx.push_back(i);
	}

	for (int i = 0; i != N; ++i) {
		in[i][0] = sin(2*pi()*50*i/N);
	}

	fftw_execute(p); /* repeat as needed */

	std::vector<double> res = tfd2vect(out, N);
	PlotCpp g;
	g.plot(xx, res);
	g.draw();


	fftw_destroy_plan(p);
	fftw_free(in); fftw_free(out);
	return app.exec();
}