def pdf_link(self, inv_link_f, y, Y_metadata):
return np.exp(self.logpdf_link(inv_link_f, y, Y_metadata))<EOL>
Likelihood function given inverse link of f.

.. math::
    p(y_{i}|\\lambda(f_{i})) = \\lambda(f_{i})^{y_{i}}(1-f_{i})^{1-y_{i}}

:param inv_link_f: latent variables inverse link of f.
:type inv_link_f: Nx1 array
:param y: data
:type y: Nx1 array
:param Y_metadata: Y_metadata must contain 'trials'
:returns: likelihood evaluated for this point
:rtype: float

.. Note:
    Each y_i must be in {0, 1}