def move_matrix(coef,mat_1,mat_2,add_mat):
    """
    Do matrix calculations without messing with numpy.

    Inputs:
        coef: coefficient for the current matrix combination
        centroid: the centroid matrix
        point: the point by which to alter the centroid

    Output: a single combined matrix, representing the new centroid
    """
    # Subtract the point from the centroid to get the new point
    new_point = coef * [map(lambda x, y: x-y, ii, jj) for ii, jj in zip(mat_1, mat_2)]
    # Add the old centroid to the new point and return
    return [map(lambda x,y: x+y, ii, jj) for ii, jj in zip(add_mat, new_point)]