commit 3c19ddec5e69f74af8f4e26ee57b910a10a83af1
Author: MaaaartinTH <vertexless@gmail.com>
Date:   Thu Oct 15 13:31:00 2026 +0200

    Erster Stand: compute.py

diff --git a/.gitignore b/.gitignore
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+.venv/
+__pycache__/
+.env
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diff --git a/AGENTS.md b/AGENTS.md
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+# Regeln für dieses Projekt
+- Code nach PEP 8, Zeilenlänge maximal 88 Zeichen.
+- Jede Funktion und Methode hat einen Docstring und Type Hints.
+- Vor jedem Commit: `ruff check` und `ruff format`.
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diff --git a/compute.py b/compute.py
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+"""Computational utilities for matrix operations and 2D transformations.
+
+Functions:
+    matmul(A, B)
+        Multiply two matrices represented as list of lists.
+    transpose(matrix)
+        Return the transpose of a matrix.
+    rot_2D(theta)
+        Return the 2D rotation matrix for a given angle theta.
+"""
+
+from __future__ import annotations
+from typing import List
+import math
+
+Matrix = List[List[float]]
+
+def transpose(matrix: Matrix) -> Matrix:
+    """Return the transpose of *matrix*.
+
+    The matrix must be non‑empty and rectangular; this is validated
+    by the existing ``_check_matrix`` helper.
+    """
+    _check_matrix(matrix)
+    rows, cols = len(matrix), len(matrix[0])
+    return [[matrix[i][j] for i in range(rows)] for j in range(cols)]
+
+def rot_2D(theta: float) -> Matrix:
+    """Return the 2D rotation matrix for a given angle theta (in radians).
+
+    Parameters
+    ----------
+    theta : float
+        Rotation angle in radians.
+
+    Returns
+    -------
+    Matrix
+        A 2x2 rotation matrix [[cos(theta), -sin(theta)], [sin(theta), cos(theta)]].
+    """
+    c = math.cos(theta)
+    s = math.sin(theta)
+    return [
+        [c, -s],
+        [s,  c]
+    ]
+
+def _check_matrix(matrix: Matrix) -> None:
+    """Ensure all rows in *matrix* are lists of floats and of equal length.
+
+    Raises:
+        ValueError: If *matrix* is empty, contains non‑list rows,
+                    non‑float elements, or uneven row lengths.
+    """
+    if not matrix:
+        raise ValueError("Matrix must not be empty")
+    row_len = None
+    for row_idx, row in enumerate(matrix):
+        if not isinstance(row, list):
+            raise ValueError(f"Row {row_idx} is not a list")
+        if row_len is None:
+            row_len = len(row)
+            if row_len == 0:
+                raise ValueError("Rows must contain at least one element")
+        elif len(row) != row_len:
+            raise ValueError(
+                f"Row {row_idx} length {len(row)} differs from expected {row_len}"
+            )
+        for col_idx, item in enumerate(row):
+            if not isinstance(item, (int, float)):
+                raise ValueError(
+                    f"Element at ({row_idx},{col_idx}) is not a number"
+                )
+
+
+def matmul(A: Matrix, B: Matrix) -> Matrix:
+    """Return the matrix product of *A* and *B*.
+
+    The matrices must be compatible for multiplication, i.e. the
+    number of columns in *A* must equal the number of rows in *B*.
+
+    Parameters
+    ----------
+    A, B : Matrix
+        Two‑dimensional lists of numeric values.
+
+    Returns
+    -------
+    Matrix
+        Resulting matrix of dimensions ``len(A) x len(B[0])``.
+
+    Raises
+    ------
+    ValueError
+        If either input is malformed (non‑uniform rows, empty,
+        non‑numeric entries) or if the dimensions are incompatible.
+    """
+    _check_matrix(A)
+    _check_matrix(B)
+
+    a_rows, a_cols = len(A), len(A[0])
+    b_rows, b_cols = len(B), len(B[0])
+
+    if a_cols != b_rows:
+        raise ValueError(
+            f"Cannot multiply: {a_rows}x{a_cols} matrix A with {b_rows}x{b_cols} matrix B"
+        )
+
+    result: Matrix = []
+    for i in range(a_rows):
+        row: List[float] = []
+        for j in range(b_cols):
+            s = 0.0
+            for k in range(a_cols):
+                s += A[i][k] * B[k][j]
+            row.append(s)
+        result.append(row)
+
+    return result
+
+if __name__ == "__main__":
+    # Test für rot_2D (z. B. Rotation um 90 Grad = pi / 2)
+    theta = math.pi / 2
+    R = rot_2D(theta)
+    print("Rotationsmatrix für 90 Grad:", R)
+
+    # Einen Punkt (Vektor) als 2x1 Matrix rotieren: [ [x], [y] ]
+    point = [[1.0], [0.0]]  # Punkt auf der x-Achse bei x=1, y=0
+    rotated_point = matmul(R, point)
+    print("Gedrehter Punkt (erwartet y=1, x=0):", rotated_point)
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diff --git a/pyproject.toml b/pyproject.toml
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+[project]
+name = "matrixmania"
+version = "0.1.0"
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