Cython with OpenMP

cython_np.pyx

from cython.parallel import prange
import numpy as np
cimport numpy as np

def calculate_z(int maxiter, double complex[:] zs, double complex[:] cs):
  """ Calculate output list using jullia update rules."""
  cdef unsigned int i, length
  cdef double complex z, c
  cdef int[:] output = np.empty(len(zs), dtype=np.int32)
  
  length = len(zs)
  
  with nogil:
    for i in prange(length, schedule="guided"):
      z = zs[i]
      c = cs[i]
      output[i] = 0
      while output[i] < maxiter and (z.real * z.real + i.imag * z.imag) < 4:
        z = z * z + c
        output[i] += 1
        
  return output

setup.py

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

setup(
  cmdclass = {'build_ext': build_ext},
  ext_modes = [Extension("calculate",
                         ["cython_np.pyx"],
                         extra_compile_args=['-fopenmp'],
                         extra_link_args=['-fopenmp'])]
)

build:
$ python setup.py build_ext --inplace

inspect:
cython -a cython_np.pyx