code: def __call__(self, v, cost, parameters, damp):
      # compute Gauss-Newton Matrix right-multiplied by `v`
      Jv = T.Rop(self._s, parameters, v)
      HJv = T.grad(
          T.sum(T.grad(cost, self._s) * Jv),
          self._s,
          consider_constant=[Jv],
      )
      JHJv = T.grad(
          T.sum(HJv * self._s), parameters, consider_constant=[HJv, Jv]
      )
  
      # apply Tikhonov damping
      JHJv = [JHJvi + damp * vi for JHJvi, vi in zip(JHJv, v)]
      return JHJv
  
imports: from __future__ import absolute_import, print_function, division
  import numpy
  import unittest
  import theano
  from theano import config
  from theano import tensor
  from theano.scan_module.scan_op import Scan
  from theano.tests import unittest_tools
label_desc: Use image node_id 2 for calling the GaussNewtonMatrix obj's underlying member method code with example usage: obj.__call__(v, cost, parameters, damp) and returns: JHJv