def central_difference(x, y):
if (len(x) != len(y)):<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>z1 = np.hstack((y[<NUM_LIT:0>], y[:-<NUM_LIT:1>]))<EOL>z2 = np.hstack((y[<NUM_LIT:1>:], y[-<NUM_LIT:1>]))<EOL>dx1 = np.hstack((<NUM_LIT:0>, np.diff(x)))<EOL>dx2 = np.hstack((np.diff(x), <NUM_LIT:0>))<EOL>return (z2 - z1) / (dx2 + dx1)<EOL>
Returns the dy/dx(x) via central difference method

    Parameters
    ----------
    x : array like
    y : array like

    Returns
    -------
    dy/dx : array like