103 lines
2.7 KiB
Python
103 lines
2.7 KiB
Python
from typing import List
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import math
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from tabulate import tabulate
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def matmul(mat1: List[List[int]], mat2: List[List[int]]) -> List[List[int]]:
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"""
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Multiplies two matrices and returns the resulting matrix.
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:param mat1: The first matrix
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:param mat2: The second matrix
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:return: A new matrix representing the product of mat1 and mat2
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:raises ValueError: If the number of columns in mat1 does not equal the number of rows in mat2
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"""
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if len(mat1[0]) != len(mat2):
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raise ValueError("Matrix isnt computable")
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mat3: List[List[int]] = []
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for i in range(len(mat1)):
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new_row: List[int] = []
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for j in range(len(mat2[0])):
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summe = 0
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for k in range(len(mat2)):
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summe += mat1[i][k] * mat2[k][j]
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new_row.append(summe)
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mat3.append(new_row)
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return mat3
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def transpose(matrix: List[List[int]]) -> List[List[int]]:
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"""
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Transposes a given matrix (rows become columns and columns become rows).
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:param matrix: A list of lists representing the matrix.
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:return: A new matrix that is the transpose of the input matrix.
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"""
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if not matrix:
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raise ValueError("Matrix is empty")
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row_length = len(matrix[0])
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if any(len(row) != row_length for row in matrix):
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raise ValueError("Matrix rows have uneven lengths")
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transposed: List[List[int]] = []
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for i in range(row_length):
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new_row = []
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for j in range(len(matrix)):
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new_row.append(matrix[j][i])
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transposed.append(new_row)
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return transposed
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def rot_2D(theta: float) -> List[List[float]]:
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"""
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Returns a 2D rotation matrix for a given angle in radians.
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The rotation matrix can be used to rotate points in the 2D plane
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around the origin by the angle theta (counterclockwise).
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:param theta: The rotation angle in radians.
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:return: A 2x2 rotation matrix as a list of lists.
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"""
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cos_t = math.cos(theta)
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sin_t = math.sin(theta)
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return [
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[cos_t, -sin_t],
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[sin_t, cos_t]
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]
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def main():
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# Test matrix multiplication
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matrix_a = [[3, 4, -1, 4],
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[-2, 2, 5, 1]]
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matrix_b = [[1, 3, -2],
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[2, 5, 1],
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[-1, 4, -4],
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[2, 3, 6]]
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matrix_c = matmul(matrix_a, matrix_b)
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print("Ergebnis C = A * B:")
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for row in matrix_c:
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print(row)
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# Test transpose
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matrix = [[1, 2, 3],
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[4, 5, 6]]
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print("\nTransposed:")
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for row in transpose(matrix):
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print(row)
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# Test rotation
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print("\nRotation matrix for 90° (pi/2 radians):")
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for row in rot_2D(math.pi / 2):
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print(row)
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print("Matrix A:")
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print(tabulate(matrix_a))
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if __name__ == "__main__":
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main()
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