Cython Numpy accumulate

accumulate.pyx

cimport numpy as np

ctypedef np.long_t DTYPE_int_t
ctypedef np.double_t DTYPE_double_t

cimport cython
@cython.boundscheck(False) # turn of bounds-checking for entire function
@cython.wraparound(False)
def accumulate(
       np.ndarray[DTYPE_double_t, ndim=1] a not None,
       np.ndarray[DTYPE_int_t, ndim=1] section_lengths not None,
       np.ndarray[DTYPE_double_t, ndim=1] out not None,
       ): 
    cdef unsigned int i_el, i_bas, sec_length, lenout
    cdef double tmp
    lenout = out.shape[0] 
    i_el = 0
    for i_bas in range(lenout):
        tmp = 0
        for sec_length in range(section_lengths[i_bas]):
            tmp += a[i_el]
            i_el+=1
        out[i_bas] = tmp
    return 0

setup.py

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

ext_modules = [Extension("accumulate", ["accumulate.pyx"], extra_compile_args=["-O3",])]

setup(
  name = 'Accumulate',
  cmdclass = {'build_ext': build_ext},
  ext_modules = ext_modules
)

cython -a output for the last line (return 0):

24:     return 0
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 *     return 0             # <<<<<<<<<<<<<<
 */
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