1 files changed, 118 insertions, 0 deletions
diff --git a/test/math/gauss.cpp b/test/math/gauss.cpp
new file mode 100644
index 0000000..37bacce
--- /dev/null
+++ b/test/math/gauss.cpp
@@ -0,0 +1,118 @@
+#include "../util.h"
+constexpr double EPS = 1e-9;
+constexpr int UNIQUE = 1;
+constexpr int INCONSISTENT = 2;
+constexpr int MULTIPLE = 3;
+vector<vector<double>> mat;
+#include <math/gauss.cpp>
+
+vector<vector<double>> inverseMat(const vector<vector<double>>& m) {
+	int n = sz(m);
+	mat = m;
+	for (int i = 0; i < n; i++) {
+		if (sz(mat[i]) != n) cerr << "error: no square matrix" << FAIL;
+		mat[i].resize(2*n);
+		mat[i][n+i] = 1;
+	}
+	gauss(n);//the unique cetc. checks are not usefull since we dont solve an lgs...
+	vector<vector<double>> res(m);
+	for (int i = 0; i < n; i++) {
+		res[i] = vector<double>(mat[i].begin() + n, mat[i].end());
+		for (int j = 0; j < n; j++) {
+			if (j != i && mat[i][j] != 0) cerr << "error: not full rank?" << FAIL;
+			if (j == i && mat[i][j] == 0) cerr << "error: not full rank?" << FAIL;
+		}
+	}
+	return res;
+}
+
+vector<vector<double>> mul(const vector<vector<double>>& a, const vector<vector<double>>& b) {
+	int n = sz(a);
+	int m = sz(b[0]);
+	int x = sz(b);
+	if (sz(a[0]) != sz(b)) cerr << "error: wrong dimensions" << FAIL;
+	vector<vector<double>> res(n, vector<double>(m));
+	for (int i = 0; i < n; i++) {
+		for (int j = 0; j < m; j++) {
+			for (int k = 0; k < x; k++) {
+				res[i][j] += a[i][k] * b[k][j];
+			}
+		}
+	}
+	return res;
+}
+
+void test_tiny() {
+	mat = {
+		{1, 2, 3, 4},
+		{0, 5, 6, 7},
+		{0, 0, 8, 9},
+	};
+	if (gauss(sz(mat)) != UNIQUE) cerr << "error: 1" << FAIL;
+
+	mat = {
+		{-1,  1, 0, -1},
+		{ 2,  6, 0, 10},
+		{ 1, -2, 0,  0},
+	};
+	if (gauss(sz(mat)) != MULTIPLE) cerr << "error: 2" << FAIL;
+
+	mat = {
+		{-1,  1, 0, -1},
+		{ 2,  6, 0, 10},
+		{ 1, -2, 0,  1},
+	};
+	if (gauss(sz(mat)) != INCONSISTENT) cerr << "error: 3" << FAIL;
+}
+
+void stress_test_inv() {
+	ll queries = 0;
+	for (int tries = 0; tries < 20'000; tries++) {
+		int n = Random::integer<int>(1, 30);
+
+		vector<vector<double>> m(n);
+		for (auto& v : m) v = Random::reals<double>(n, 0, 1'000);
+		// m hopefully has full rank...
+
+		auto inv = inverseMat(m);
+
+		auto prod = mul(m, inv);
+
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j < n; j++) {
+				if (i == j && abs(prod[i][j] - 1) >= EPS) cerr << "error: not inverted " << prod[i][j] << FAIL;
+				if (i != j && abs(prod[i][j] - 0) >= EPS) cerr << "error: not inverted " << prod[i][j] << FAIL;
+			}
+		}
+
+		queries += n;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 250;
+void performance_test() {
+	timer t;
+
+	vector<vector<double>> m(N);
+	for (auto& v : m) v = Random::reals<double>(N, 0, 1'000);
+	mat = m;
+
+	t.start();
+	gauss(N);
+	t.stop();
+	hash_t hash = 0;
+	for (int i = 0; i < N; i++) {
+		for (int j = 0; j < N; j++) {
+			hash += mat[i][j];
+		}
+	}
+	if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	test_tiny();
+	stress_test_inv();
+	performance_test();
+}