diff --git a/matrix/matrix_multiplication_addition.py b/matrix/matrix_multiplication_addition.py index c387c43d4..dd50db729 100644 --- a/matrix/matrix_multiplication_addition.py +++ b/matrix/matrix_multiplication_addition.py @@ -10,6 +10,8 @@ def add(matrix_a, matrix_b): matrix_c.append(list_1) return matrix_c +def scalarMultiply(matrix , n): + return [[x * n for x in row] for row in matrix] def multiply(matrix_a, matrix_b): matrix_c = [] @@ -24,13 +26,50 @@ def multiply(matrix_a, matrix_b): matrix_c.append(list_1) return matrix_c +def identity(n): + return [[int(row == column) for column in range(n)] for row in range(n)] + +def transpose(matrix): + return map(list , zip(*matrix)) + +def minor(matrix, row, column): + minor = matrix[:row] + matrix[row + 1:] + minor = [row[:column] + row[column + 1:] for row in minor] + return minor + +def determinant(matrix): + if len(matrix) == 1: return matrix[0][0] + + res = 0 + for x in range(len(matrix)): + res += matrix[0][x] * determinant(minor(matrix , 0 , x)) * (-1) ** x + return res + +def inverse(matrix): + det = determinant(matrix) + if det == 0: return None + + matrixMinor = [[] for _ in range(len(matrix))] + for i in range(len(matrix)): + for j in range(len(matrix)): + matrixMinor[i].append(determinant(minor(matrix , i , j))) + + cofactors = [[x * (-1) ** (row + col) for col, x in enumerate(matrixMinor[row])] for row in range(len(matrix))] + adjugate = transpose(cofactors) + return scalarMultiply(adjugate , 1/det) def main(): matrix_a = [[12, 10], [3, 9]] matrix_b = [[3, 4], [7, 4]] + matrix_c = [[11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34], [41, 42, 43, 44]] + matrix_d = [[3, 0, 2], [2, 0, -2], [0, 1, 1]] + print(add(matrix_a, matrix_b)) print(multiply(matrix_a, matrix_b)) - + print(identity(5)) + print(minor(matrix_c , 1 , 2)) + print(determinant(matrix_b)) + print(inverse(matrix_d)) if __name__ == '__main__': main()