import numpy as np


def sp_jk(freq_bins, amp_spectra):
    # Calculate source parameters using J and K Snoke's integrals
    # with correction for the limited frequency band. The routine
    # ignores quality factor in calculations (ideally, the spectrum
    # should be corrected for attenuation before).

    # For each waveform, calculate the J and K integrals and source parameters.

    Av = amp_spectra * 2 * np.pi * freq_bins

    jf = (2 * np.trapz(Av ** 2, x=freq_bins) + 2 / 3 * (amp_spectra[0] * 2 * np.pi * freq_bins[0]) ** 2 *
          freq_bins[0] + 2 * (amp_spectra[-1] * 2 * np.pi * freq_bins[-1]) ** 2 * freq_bins[-1])

    kf = (2 * np.trapz(amp_spectra ** 2, x=freq_bins) + 2 * amp_spectra[0] ** 2 * freq_bins[0] +
          2 / 3 * amp_spectra[-1] ** 2 * freq_bins[-1])

    # Calculation of spectral level and corner frequency
    mo = 2 * (kf ** 3 / jf) ** 0.25  # spectral level from Snoke's integrals
    fo = np.sqrt(jf / kf) / (2 * np.pi)  # corner frequency

    return mo, fo