My implementation of rotating a quad matrix (90° clockwise)

matrix-rotate.py

#! /usr/bin/env python3

def rotate(matrix):
    """
    Do not return anything, modify matrix in-place instead.
    """
    n = len(matrix)
    x = 0
    y = 0

    med = 0
    if n % 2 == 0:
        med = int(n / 2)
    else:
        med = int(n / 2) + 1
    print("med " + str(med))

    for y in range(med):
        x_max = n - y - 1
        if n % 2 != 0 and x_max == y:
            x_max += 1

        for x in range(y, x_max):
            print("y:" + str(y) + " x:" + str(x))
            y1 = y
            x1 = x
            new_val = matrix[y1][x1]
            for i in range(4):
                old_val = new_val
                print(y1, x1)
                y2 = y1
                y1 = x1
                x1 = n - y2 - 1
                print(n)
                print(y1, x1)
                print("---")
                new_val = matrix[y1][x1]
                matrix[y1][x1] = old_val

# a = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
# m = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
# e = [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

# a = [[1,2,3],[4,5,6],[7,8,9]]
# m = [[1,2,3],[4,5,6],[7,8,9]]
# e = [[7,4,1],[8,5,2],[9,6,3]]

# a = [[2,29,20,26,16,28],[12,27,9,25,13,21],[32,33,32,2,28,14],[13,14,32,27,22,26],[33,1,20,7,21,7],[4,24,1,6,32,34]]
# m = [[2,29,20,26,16,28],[12,27,9,25,13,21],[32,33,32,2,28,14],[13,14,32,27,22,26],[33,1,20,7,21,7],[4,24,1,6,32,34]]
# e = [[4,33,13,32,12,2],[24,1,14,33,27,29],[1,20,32,32,9,20],[6,7,27,2,25,26],[32,21,22,28,13,16],[34,7,26,14,21,28]]

a = [[43,39,3,33,37,20,14],[9,18,9,-1,40,22,38],[14,42,3,23,12,14,32],[18,31,45,11,8,-1,31],[28,44,14,23,40,24,13],[29,45,33,45,20,0,45],[12,23,35,32,22,39,8]]
m = [[43,39,3,33,37,20,14],[9,18,9,-1,40,22,38],[14,42,3,23,12,14,32],[18,31,45,11,8,-1,31],[28,44,14,23,40,24,13],[29,45,33,45,20,0,45],[12,23,35,32,22,39,8]]
e = [[12,29,28,18,14,9,43],[23,45,44,31,42,18,39],[35,33,14,45,3,9,3],[32,45,23,11,23,-1,33],[22,20,40,8,12,40,37],[39,0,24,-1,14,22,20],[8,45,13,31,32,38,14]]

rotate(m)

print(a)
print(m)
print(e)