code: def test_vonneumann_entropy_mixed_state():
      """Test for vonneumann_entropy on 2-dimensional tensors.
      This test checks that the VNE of mixed states is calculated correctly.
      """
      state1 = tl.tensor(
          [
              [
                  0.03004805,
                  0.42426117,
                  0.5483771,
                  0.4784077,
                  0.25792725,
                  0.34388784,
                  0.99927586,
                  0.96605812,
              ]
          ]
      )
      state1 = state1 / tl.norm(state1)
      state2 = tl.tensor(
          [
              [
                  0.84250089,
                  0.43429687,
                  0.26551928,
                  0.18262211,
                  0.55584835,
                  0.2565509,
                  0.33197401,
                  0.97741178,
              ]
          ]
      )
      state2 = state2 / tl.norm(state2)
      mat_mixed = tl.tensor(
          (
              tl.dot(tl.transpose(state1), state1)
              + tl.dot(tl.transpose(state2), state2)
          )
          / 2.0
      )
      tensor_mixed = tl.reshape(mat_mixed, (4, 2, 4, 2))
      actual_vne = 0.5546
      tl_vne = vonneumann_entropy(mat_mixed)
      tl_tensor_vne = vonneumann_entropy(tensor_mixed)
      assert_array_almost_equal(tl_vne, actual_vne, decimal=3)
      assert_array_almost_equal(tl_tensor_vne, actual_vne, decimal=3)
  
file_path: tensorly/tensorly/metrics/tests/test_entropy.py
imports: import tensorly
  from ..entropy import vonneumann_entropy
  from ..entropy import tt_vonneumann_entropy, cp_vonneumann_entropy
  from ...decomposition import parafac, tensor_train
  from tensorly.testing import assert_array_almost_equal
label_desc: Use image node_id 4 for calling a global function with example usage: test_vonneumann_entropy_mixed_state() without return types