matrix_3by3solve.py

Created on September 10, 2023
1.48 KB
get det & inverse of matrix
# Define a new 3x3 matrix A

A=int(input("A: "))
B=int(input("B: "))
C=int(input("C: "))

D=int(input("D: "))
E=int(input("E: "))
F=int(input("F: "))

G=int(input("G: "))
H=int(input("H: "))
I=int(input("I: "))





A = [[A, B, C],
     [D, E, F],
     [G, H, I]]

# Calculate the determinant of A manually
det_A = (A[0][0] * (A[1][1] * A[2][2] - A[1][2] * A[2][1]) -
         A[0][1] * (A[1][0] * A[2][2] - A[1][2] * A[2][0]) +
         A[0][2] * (A[1][0] * A[2][1] - A[1][1] * A[2][0]))

# Check if the determinant is zero (for invertibility)
if det_A == 0:
    print("The matrix is not invertible (determinant is zero).")
else:
    # Calculate the inverse of A manually with rounding
    A_inverse = [[round((A[1][1] * A[2][2] - A[1][2] * A[2][1]) / det_A, 3),
                  round((A[0][2] * A[2][1] - A[0][1] * A[2][2]) / det_A, 3),
                  round((A[0][1] * A[1][2] - A[0][2] * A[1][1]) / det_A, 3)],
                 [round((A[1][2] * A[2][0] - A[1][0] * A[2][2]) / det_A, 3),
                  round((A[0][0] * A[2][2] - A[0][2] * A[2][0]) / det_A, 3),
                  round((A[0][2] * A[1][0] - A[0][0] * A[1][2]) / det_A, 3)],
                 [round((A[1][0] * A[2][1] - A[1][1] * A[2][0]) / det_A, 3),
                  round((A[0][1] * A[2][0] - A[0][0] * A[2][1]) / det_A, 3),
                  round((A[0][0] * A[1][1] - A[0][1] * A[1][0]) / det_A, 3)]]

    # Print the rounded inverse
    print("Inverse of A:")
    for row in A_inverse:
        print(row)