def sigma(htilde, psd = None, low_frequency_cutoff=None,
        high_frequency_cutoff=None):
    """ Return the sigma of the waveform. See sigmasq for more details.

    Parameters
    ----------
    htilde : TimeSeries or FrequencySeries
        The input vector containing a waveform.
    psd : {None, FrequencySeries}, optional
        The psd used to weight the accumulated power.
    low_frequency_cutoff : {None, float}, optional
        The frequency to begin considering waveform power.
    high_frequency_cutoff : {None, float}, optional
        The frequency to stop considering waveform power.

    Returns
    -------
    sigmasq: float
    """
    return sqrt(sigmasq(htilde, psd, low_frequency_cutoff, high_frequency_cutoff))
Return the sigma of the waveform. See sigmasq for more details.

    Parameters
    ----------
    htilde : TimeSeries or FrequencySeries
        The input vector containing a waveform.
    psd : {None, FrequencySeries}, optional
        The psd used to weight the accumulated power.
    low_frequency_cutoff : {None, float}, optional
        The frequency to begin considering waveform power.
    high_frequency_cutoff : {None, float}, optional
        The frequency to stop considering waveform power.

    Returns
    -------
    sigmasq: float