1 files changed, 51 insertions, 0 deletions
diff --git a/test/math/transforms/fft.cpp b/test/math/transforms/fft.cpp
new file mode 100644
index 0000000..858676b
--- /dev/null
+++ b/test/math/transforms/fft.cpp
@@ -0,0 +1,51 @@
+#include "../../util.h"
+#include <math/transforms/fft.cpp>
+
+vector<cplx> to_cplx(const vector<ll>& in) {
+	vector<cplx> res(sz(in));
+	for (int i = 0; i < sz(in); i++) res[i] = in[i];
+	return res;
+}
+
+vector<ll> from_cplx(const vector<cplx>& in) {
+	vector<ll> res(sz(in));
+	for (int i = 0; i < sz(in); i++) res[i] = llround(real(in[i]));
+	return res;
+}
+
+void stress_test() {
+	ll queries = 0;
+	for (ll i = 0; i < 10'000; i++) {
+		int n = 1ll << Random::integer<int>(0, 10);
+		auto expected = Random::integers<ll>(n, -1000, 1000);
+		vector<cplx> tmp = to_cplx(expected);
+		fft(tmp, false);
+		fft(tmp, true);
+		auto got = from_cplx(tmp);
+		if (got != expected) cerr << "error" << FAIL;
+		queries += n;
+	}
+	cerr << "tested queries: " << queries << endl;
+}
+
+constexpr int N = 1ll << 21;
+void performance_test() {
+	timer t;
+	auto a = to_cplx(Random::integers<ll>(N, -1000, 1000));
+	auto b = to_cplx(Random::integers<ll>(N, -1000, 1000));
+	t.start();
+	fft(a, true);
+	fft(b, false);
+	t.stop();
+	hash_t hash = 0;
+	for (ll i = 0; i < N; i++) hash += i * llround(real(a[i]));
+	for (ll i = 0; i < N; i++) hash += i * llround(real(b[i]));
+	if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	stress_test();
+	performance_test();
+}
+