code: def x_tx(x):
      """Inner product
      :math:`x^T x`
  
      Parameters
      -----------
      x : tf.Tensor
  
      """
      return tf.matmul(x, x, transpose_a=True)
  
file_path: brainiak/brainiak/matnormal/utils.py
imports: import tensorflow
  import tensorflow_probability
  from scipy.stats import norm
  from numpy.linalg import cholesky
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: x_tx(x) and returns: tf