def rotate():
    i, j = 0, 0
    c, s = 0, 0

    for i in range(0, n):
        for j in range(i + 1, n):
            a = matrix[i, i]
            b = matrix[j, i]
            c = a / m.sqrt(a*a + b*b)
            s = b / m.sqrt(a*a + b*b)
            for k in range(i, n+1):
                t = matrix[i, k]
                matrix[i, k] = (c * matrix[i, k]) + (s * matrix[j, k])
                matrix[j, k] = (-s * t) + (c * matrix[j, k])

    for i in range(n-1, 0, -1):
        summ = 0
        for j in range(i + 1, n):
            summ += matrix[i, j] * x[j]
        summ = matrix[i, n] - summ
        if matrix[i, i] == 0:
            return False
            exit()
        x[i] = summ / matrix[i, i]