code: def _get_search_direction(inv_hessian_approx, gradient):
      """Computes the direction along which to perform line search."""
      return -tf.linalg.matvec(inv_hessian_approx, gradient)
  
file_path: probability/tensorflow_probability/python/optimizer/bfgs.py
imports: import collections
  import tensorflow.compat.v2
  from tensorflow_probability.python.internal import distribution_util
  from tensorflow_probability.python.internal import dtype_util
  from tensorflow_probability.python.internal import prefer_static
  from tensorflow_probability.python.optimizer import bfgs_utils
label_desc: Use image node_id 3 for calling a global function with example usage: _get_search_direction(inv_hessian_approx, gradient) and returns: unknown