initial project structure

src/matrixmania/__init__.py

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+from .compute import matmul, transpose, rot_2d

src/matrixmania/compute.py

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+"""Utility module providing basic matrix operations.
+
+Functions
+---------
+- :func:`matmul` – Multiply two matrices.
+- :func:`transpose` – Transpose a matrix.
+- :func:`rotate` – Rotate a matrix 90° clockwise.
+
+All functions work on nested Python lists and perform basic
+validation before operation.
+"""
+
+from __future__ import annotations
+
+Matrix = list[list[float]]
+
+def main():
+    a = [[1, 2, 3], [4, 5, 6]]
+    b = [[7, 8], [10, 11], [12, 13]]
+    print(matmul(a,b))
+    print(rotate(a))
+    print(transpose(a))
+
+def matmul(a: Matrix, b: Matrix) -> Matrix:
+    """Return the product of two matrices.
+
+    Parameters
+    ----------
+    a: Matrix
+        Left‑hand matrix (shape ``m × n``).
+    b: Matrix
+        Right‑hand matrix (shape ``n × p``).
+
+    Returns
+    -------
+    Matrix
+        Resulting matrix of shape ``m × p``.
+
+    Raises
+    ------
+    ValueError
+        If the inner dimensions of the matrices do not match, or if
+        either argument is empty.
+    """
+    if not a or not a[0] or not b or not b[0]:
+        raise ValueError("Input matrices must be non‑empty")
+
+    n_cols_a = len(a[0])
+    n_rows_b = len(b)
+    if n_cols_a != n_rows_b:
+        raise ValueError(
+            f"Inner dimensions must agree for matrix multiplication: "
+            f"{len(a)}×{n_cols_a} and {n_rows_b}×{len(b[0])}"
+        )
+
+    m = len(a)
+    p = len(b[0])
+    result: Matrix = [[0.0 for _ in range(p)] for _ in range(m)]
+
+    for i in range(m):
+        for j in range(p):
+            total = 0.0
+            for k in range(n_cols_a):
+                total += a[i][k] * b[k][j]
+            result[i][j] = total
+    return result
+
+
+def transpose(matrix: Matrix) -> Matrix:
+    """Return the transpose of a matrix.
+
+    Parameters
+    ----------
+    matrix: Matrix
+        A matrix represented as a list of row lists.
+
+    Returns
+    -------
+    Matrix
+        The transposed matrix.
+
+    Raises
+    ------
+    ValueError
+        If the matrix is empty or rows are not of equal length.
+    """
+    if not matrix or not matrix[0]:
+        raise ValueError("Input matrix must be non‑empty")
+
+    row_length = len(matrix[0])
+    for row in matrix:
+        if len(row) != row_length:
+            raise ValueError("All rows in the matrix must have the same length")
+
+    return [list(col) for col in zip(*matrix)]
+
+
+def rot_2d(matrix: Matrix) -> Matrix:
+    """Return the matrix rotated 90 degrees clockwise.
+
+    This is equivalent to transposing the matrix and then reversing
+    each row.
+
+    Parameters
+    ----------
+    matrix: Matrix
+        A matrix represented as a list of row lists.
+
+    Returns
+    -------
+    Matrix
+        The rotated matrix.
+
+    Raises
+    ------
+    ValueError
+        If the matrix is empty or rows are not of equal length.
+    """
+    transposed = transpose(matrix)
+    return [list(reversed(row)) for row in transposed]
+
+if __name__ == "__main__":
+    main()
+
+"""End of module"""