code: def test_multiple_fast_inv():
      shape = (10, 20, 20)
      X = np.random.randn(*shape)
      X_inv_ref = np.zeros(shape)
      for i in range(shape[0]):
          X[i] = np.dot(X[i], X[i].T)
          X_inv_ref[i] = spl.inv(X[i])
      X_inv = multiple_fast_inv(X)
      assert_array_almost_equal(X_inv_ref, X_inv)
  
file_path: nipy/nipy/algorithms/statistics/tests/test_utils.py
imports: import numpy
  import pytest
  import scipy.linalg
  from numpy.testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal
  from scipy.stats import norm
  from ..utils import check_cast_bin8, multiple_fast_inv, multiple_mahalanobis, z_score
label_desc: Use image node_id 4 for calling a global function with example usage: test_multiple_fast_inv() without return types