code: def skew_normal_like(x, mu, tau, alpha):
      R
      return flib.sn_like(x, mu, tau, alpha)
docs: R"""
      Azzalini's skew-normal log-likelihood
  
      .. math::
          f(x \mid \mu, \tau, \alpha) = 2 \Phi((x-\mu)\sqrt{\tau}\alpha) \phi(x,\mu,\tau)
  
      where :math:\Phi is the normal CDF and :math: \phi is the normal PDF.
  
      :Parameters:
        - `x` : Input data.
        - `mu` : Mean of the distribution.
        - `tau` : Precision of the distribution (> 0).
        - `alpha` : Shape parameter of the distribution.
  
      .. note::
        See http://azzalini.stat.unipd.it/SN/