diff --git a/pyproject.toml b/pyproject.toml
index fa29cc7..f2ac542 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,6 +2,7 @@
 name = "matrixmania"
 version = "0.1.0"
 dependencies = ["tabulate", "ruff"]
+
 [project.optional-dependencies]
 dev = ["pytest", "ruff", "pytest-cov"]
 
diff --git a/src/matrixmania/compute.py b/src/matrixmania/compute.py
index 7a09f52..2a11f7a 100644
--- a/src/matrixmania/compute.py
+++ b/src/matrixmania/compute.py
@@ -104,6 +104,65 @@ def rot_2D(winkel):
     ]
 
 def rot_3D(angle: float, axis: str) -> list[list[float]]:
+    """Gibt die Rotationsmatrix für einen Winkel in Radiant um die x-, y- oder z-Achse zurück.
+
+    Parameters
+    ----------
+    angle : float
+        Rotationswinkel in Radiant.
+    axis : str
+        Rotationsachse: ``"x"``, ``"y"`` oder ``"z"``.
+
+    Returns
+    -------
+    list[list[float]]
+        Die entsprechende 3x3-Rotationsmatrix.
+
+    Raises
+    ------
+    ValueError
+        Wenn ``axis`` nicht ``"x"``, ``"y"`` oder ``"z"`` ist.
+
+    Formeln
+    -------
+    Rx(theta) =
+        [[1, 0, 0],
+         [0, cos(theta), -sin(theta)],
+         [0, sin(theta), cos(theta)]]
+
+    Ry(theta) =
+        [[cos(theta), 0, sin(theta)],
+         [0, 1, 0],
+         [-sin(theta), 0, cos(theta)]]
+
+    Rz(theta) =
+        [[cos(theta), -sin(theta), 0],
+         [sin(theta), cos(theta), 0],
+         [0, 0, 1]]
+    """
+    if axis == "x":
+        return [
+            [1.0, 0.0, 0.0],
+            [0.0, math.cos(angle), -math.sin(angle)],
+            [0.0, math.sin(angle), math.cos(angle)],
+        ]
+
+    if axis == "y":
+        return [
+            [math.cos(angle), 0.0, math.sin(angle)],
+            [0.0, 1.0, 0.0],
+            [-math.sin(angle), 0.0, math.cos(angle)],
+        ]
+
+    if axis == "z":
+        return [
+            [math.cos(angle), -math.sin(angle), 0.0],
+            [math.sin(angle), math.cos(angle), 0.0],
+            [0.0, 0.0, 1.0],
+        ]
+
+    raise ValueError("axis must be 'x', 'y' or 'z'")
+
 def transpose(a: list[list[float]]) -> list[list[float]]:
     """Gibt die transponierte Matrix a zurück."""
     return [
diff --git a/test/test_matrixmania/__init__.py b/test/test_matrixmania/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/test/test_matrixmania/test_rot.py b/test/test_matrixmania/test_rot.py
new file mode 100644
index 0000000..84a8969
--- /dev/null
+++ b/test/test_matrixmania/test_rot.py
@@ -0,0 +1,30 @@
+import math
+import pytest
+
+from matrixmania.compute import rot_2D, rot_3D
+
+def test_rot2D_90_grad(): # dreht es sich wirklich um 90 grad?
+    #Arrange
+    angle = math.pi/2
+    expected = [
+        [math.cos(angle), -math.sin(angle)],
+        [math.sin(angle), math.cos(angle)]
+    ]
+
+    #Act
+    result = rot_2D(angle)
+    #Assert
+    assert result == expected
+
+def test_rot3D_drehen(): #dreht sich  um 90 grad?
+    #Arrange
+    angle = math.pi/2
+    achse = "z"
+    expected = [
+        [math.cos(angle), -math.sin(angle), 0.0],
+        [math.sin(angle), math.cos(angle), 0.0],
+        [0.0, 0.0, 1.0],
+    ]
+
+    result = rot_3D(angle, achse)
+    assert result == expected
\ No newline at end of file