lab3: det Gauss

Л3-В6/Программа/src/main.py

@@ -0,0 +1,68 @@
+import numpy as np
+
+
+def det(matrix: np.matrix):
+    if matrix.shape[0] != matrix.shape[1]:
+        return None
+    if matrix.shape[0] == 1:
+        return matrix[0, 0]
+
+    return _det(matrix)
+
+
+def _det(matrix: np.matrix):
+    matrix, swaps = triangle(np.copy(matrix))
+    if matrix is None:
+        return 0.0
+
+    n = matrix.shape[0]
+    determinant = (-1) ** swaps
+    for i in range(n):
+        determinant *= matrix[i, i]
+
+    return determinant
+
+
+def triangle(matrix: np.matrix):
+    swaps = 0
+    n = matrix.shape[0]
+
+    for i in range(n):
+        if matrix[i, i] == 0:
+            if not swap_first_non_zero(matrix, i):
+                return None, swaps
+            swaps += 1
+
+        for j in range(i + 1, n):
+            matrix[j, :] = matrix[j, :] - matrix[i, :] * (matrix[j, i] / matrix[i, i])
+
+    return matrix, swaps
+
+
+def swap_first_non_zero(matrix, i):
+    n = matrix.shape[0]
+    for j in range(i + 1, n):
+        if matrix[j, i] != 0:
+            matrix[[i, j], :] = matrix[[j, i], :]
+            return True
+    return False
+
+
+A = np.matrix(
+    [
+        [4.3, -12.1, 23.2, -14.1],
+        [2.4, -4.4, 3.5, 5.5],
+        [5.4, 8.3, -7.4, 12.7],
+        [6.3, -7.6, 1.34, 3.7],
+    ],
+    dtype=np.float64,
+)
+
+print(det(A))
+print(np.linalg.det(A))
+
+print(A)
+
+B = np.matrix([[-14.4, 6.6, 9.4, 7.3]], dtype=np.float64).T
+
+# X = np.linalg.inv(A) * B