def calculate_chisq_bins(self, template, psd):
        """ Obtain the chisq bins for this template and PSD.
        """
        num_bins = int(self.parse_option(template, self.num_bins))
        if hasattr(psd, 'sigmasq_vec') and \
                                       template.approximant in psd.sigmasq_vec:
            kmin = int(template.f_lower / psd.delta_f)
            kmax = template.end_idx
            bins = power_chisq_bins_from_sigmasq_series(
                   psd.sigmasq_vec[template.approximant], num_bins, kmin, kmax)
        else:
            bins = power_chisq_bins(template, num_bins, psd, template.f_lower)
        return bins
Obtain the chisq bins for this template and PSD.