code: def test_onenormest_linear_operator(self):
      # Define a matrix through its product A B.
      # Depending on the shapes of A and B,
      # it could be easy to multiply this product by a small matrix,
      # but it could be annoying to look at all of
      # the entries of the product explicitly.
      np.random.seed(1234)
      n = 6000
      k = 3
      A = np.random.randn(n, k)
      B = np.random.randn(k, n)
      fast_estimate = self._help_product_norm_fast(A, B)
      exact_value = self._help_product_norm_slow(A, B)
      assert_(
          fast_estimate <= exact_value <= 3 * fast_estimate,
          "fast: %g\nexact:%g" % (fast_estimate, exact_value),
      )
  
imports: from __future__ import division, print_function, absolute_import
  import numpy
  from numpy.testing import assert_allclose, assert_equal, assert_
  import pytest
  import scipy.linalg
  import scipy.sparse.linalg
  from scipy.sparse.linalg._onenormest import _onenormest_core, _algorithm_2_2
label_desc: Use image node_id 7 for calling the TestOnenormest obj's underlying member method code with example usage: obj.test_onenormest_linear_operator() without return types