def normalize(y, x=None):
<EOL>if x is not None:<EOL><INDENT>x = ms(x)<EOL><DEDENT>else:<EOL><INDENT>x = <NUM_LIT:1.0><EOL><DEDENT>return y * np.sqrt( x / ms(y) )<EOL>
normalize power in y to a (standard normal) white noise signal.
    Optionally normalize to power in signal `x`.
    #The mean power of a Gaussian with :math:`\\mu=0` and :math:`\\sigma=1` is 1.