code: def _vonmises_pdf(x, mu, kappa):
      """Calculate vonmises_pdf."""
      if kappa <= 0:
          raise ValueError("Argument 'kappa' must be positive.")
      pdf = (
          1
          / (2 * np.pi * ive(0, kappa))
          * np.exp(np.cos(x - mu) - 1) ** kappa
      )
      return pdf
  
imports: import warnings
  import numpy
  from scipy.fftpack import fft
  from scipy.optimize import brentq
  from scipy.signal import convolve, convolve2d, gaussian
  from scipy.sparse import coo_matrix
  from scipy.special import ive
  from ..utils import _cov, _dot, _stack, conditional_jit
label_desc: Use image node_id 7 for calling a global function with example usage: _vonmises_pdf(x, mu, kappa) and returns: pdf