code: def test_wright_bessel_iv(b, x):
      """Test relation of wright_bessel and modified bessel function iv.
  
      iv(z) = (1/2*z)**v * Phi(1, v+1; 1/4*z**2).
      See https://dlmf.nist.gov/10.46.E2
      """
      if x != 0:
          v = b - 1
          wb = wright_bessel(1, v + 1, x**2 / 4.0)
          # Note: iv(v, x) has precision of less than 1e-12 for some cases
          # e.g v=1-1e-6 and x=1e-06)
          assert_allclose(
              np.power(x / 2.0, v) * wb,
              sc.iv(v, x),
              rtol=1e-11,
              atol=1e-11,
          )
  
file_path: scipy/scipy/special/tests/test_wright_bessel.py
imports: import pytest
  import numpy
  from numpy.testing import assert_equal, assert_allclose
  import scipy.special
  from scipy.special import rgamma, wright_bessel
label_desc: Use image node_id 2 for calling a global function with example usage: test_wright_bessel_iv(b, x) without return types