diff --git a/docs/tests.cpp b/docs/tests.cpp
index 7c928ae..756c871 100644
--- a/docs/tests.cpp
+++ b/docs/tests.cpp
@@ -1,3 +1,137 @@
 //
 // Created by marco on 03.11.2025.
-//
+// Changeb by marco on 16.11.2025
+
+#include <iostream>
+#include <cmath>
+#include "gamematrix.h"
+
+using namespace Matrix3D;
+
+bool nearlyEqual(double a, double b, double eps = 1e-6) {
+    return std::abs(a - b) < eps;
+}
+
+void test_matmul_identity() {
+    Mat4 A = identity();
+    Mat4 B = identity();
+    Mat4 R = matmul(A, B);
+
+    std::cout << "Test matmul: Identity * Identity -> Identity: ";
+
+    bool ok = true;
+    for(int i=0;i<4;i++){
+        for(int j=0;j<4;j++){
+            double expected = (i==j ? 1.0 : 0.0);
+            if(!nearlyEqual(R[i][j], expected)) ok = false;
+        }
+    }
+
+    std::cout << (ok ? "OK\n" : "FAIL\n");
+}
+
+void test_matmul_example() {
+    Mat4 A = {{
+        {{1, 2, 3, 4}},
+        {{0, 1, 2, 3}},
+        {{0, 0, 1, 2}},
+        {{0, 0, 0, 1}}
+    }};
+
+    Mat4 B = {{
+        {{1, 0, 0, 0}},
+        {{1, 1, 0, 0}},
+        {{1, 1, 1, 0}},
+        {{1, 1, 1, 1}}
+    }};
+
+    Mat4 R = matmul(A, B);
+
+    std::cout << "Test matmul: Beispielmatrizen A * B: ";
+
+    // Erwartete Matrix mit Handrechnung:
+    Mat4 Expected = {{
+        {{1+2+3+4,   2+3+4,   3+4,   4}},
+        {{0+1+2+3,   1+2+3,   2+3,   3}},
+        {{0+0+1+2,   0+1+2,   1+2,   2}},
+        {{1,         1,       1,     1}}
+    }};
+
+    bool ok = true;
+    for(int i=0;i<4;i++){
+        for(int j=0;j<4;j++){
+            if(!nearlyEqual(R[i][j], Expected[i][j])) ok = false;
+        }
+    }
+
+    std::cout << (ok ? "OK\n" : "FAIL\n");
+}
+
+void test_translate() {
+    Vec3 v{1,2,3};
+    Mat4 T = translate({5,-2,1});
+    Vec3 out = T * v;
+
+    std::cout << "Test translate (Vec3{1,2,3} + {5,-2,1}): ";
+
+    if(nearlyEqual(out.x, 6) && nearlyEqual(out.y, 0) && nearlyEqual(out.z, 4))
+        std::cout << "OK\n";
+    else
+        std::cout << "FAIL (" << out.x << "," << out.y << "," << out.z << ")\n";
+}
+
+void test_rotZ_90() {
+    Vec3 v{1,0,0};
+    Mat4 Rm = rot3D(90, 'z');
+    Vec3 out = Rm * v;
+
+    std::cout << "Test rot3D Z 90° (1,0,0 -> 0,1,0): ";
+
+    if(nearlyEqual(out.x, 0) && nearlyEqual(out.y, 1))
+        std::cout << "OK\n";
+    else
+        std::cout << "FAIL (" << out.x << "," << out.y << "," << out.z << ")\n";
+}
+
+void test_rotX_180() {
+    Vec3 v{0,1,0};
+    Mat4 Rm = rot3D(180, 'x');
+    Vec3 out = Rm * v;
+
+    std::cout << "Test rot3D X 180° (0,1,0 -> 0,-1,0): ";
+
+    if(nearlyEqual(out.y, -1))
+        std::cout << "OK\n";
+    else
+        std::cout << "FAIL (" << out.x << "," << out.y << "," << out.z << ")\n";
+}
+
+void test_rotY_270() {
+    Vec3 v{1,0,0};
+    Mat4 Rm = rot3D(270, 'y');
+    Vec3 out = Rm * v;
+
+    std::cout << "Test rot3D Y 270° (1,0,0 -> 0,0,-1): ";
+
+    if(nearlyEqual(out.x, 0) && nearlyEqual(out.z, -1))
+        std::cout << "OK\n";
+    else
+        std::cout << "FAIL (" << out.x << "," << out.y << "," << out.z << ")\n";
+}
+
+int main() {
+    std::cout << "===== Matrix3D Tests =====\n";
+
+    test_matmul_identity();
+    test_matmul_example();
+
+    test_translate();
+
+    test_rotZ_90();
+    test_rotX_180();
+    test_rotY_270();
+
+    std::cout << "==========================\n";
+    return 0;
+}
+