APS make_frequency_information function.

make_frequency_information.py

    def make_frequency_information(self):
      """NB kUseNewFFTMethod = True for MATLAB algorithm."""
        reference = self.measurement.reference
        if len(reference) > 1:
            dt = self.measurement.optical_delay_spacing
            t_offset = self.measurement.optical_delay_offset
            f_max = 1./(2*dt)
            if kUseNewFFTMethod:
                freq = np.linspace(0.0, f_max, len(reference) + 1)
            else:
                freq = np.linspace(0.0, f_max, 1+len(reference)/2.)

        else:
            f_max = 40.0
            dt = 1./(2*f_max)  # in ps
            if kUseNewFFTMethod:
                t_offset = -2048*dt
                freq = np.linspace(0.0, f_max, 2048)
            else:
                t_offset = -1024*dt
                freq = np.linspace(0.0, f_max, 1024)
        # freq array, spacing, offset
        return freq, dt, t_offset