code: def sinegauss_a(t, t0, f0, a):
      """Sine-gaussian wavelet.
  
      Differs from the ``astroML.fourier.sinegauss`` in that instead of taking a
      coefficient ``Q`` and calculating the coefficient ``a``, it assumes the
      given coefficient ``a`` is correct. The relationship between the two is
      given as:
  
          a = (f0 * 1. / Q) ** 2
      """
      return np.exp(-a * (t - t0) ** 2) * np.exp(
          2j * np.pi * f0 * (t - t0)
      )
  
file_path: astroML/astroML/tests/test_fourier.py
imports: import pytest
  import numpy
  from numpy.testing import assert_allclose
  from astroML.fourier import FT_continuous, IFT_continuous, PSD_continuous, sinegauss, sinegauss_FT
label_desc: Use image node_id 2 for calling a global function with example usage: sinegauss_a(t, t0, f0, a) and returns: unknown