How to make 2d array fast in cython

[Raphael C]

I have some code which I am trying to make fast using cython. It takes in a numpy 2d array of floating point numbers and outputs a floating point number.  Here is my attempted so far.

from __future__ import division

import numpy as np

cimport numpy as np

DTYPE_int = np.int

ctypedef np.int_t DTYPE_int_t

DTYPE_float = np.float64

ctypedef np.float64_t DTYPE_float_t

def permfunc(np.ndarray [DTYPE_float_t, ndim =2] M):

    cdef int n = M.shape[0]

    cdef np.ndarray[DTYPE_int_t, ndim =1] d = np.ones(n, dtype=DTYPE_int)

    cdef int j =  0

    cdef int s = 1

    cdef np.ndarray [DTYPE_int_t, ndim =1] f = np.arange(n, dtype=DTYPE_int)

    cdef np.ndarray [DTYPE_float_t, ndim =1] v = M.sum(axis=0)

    cdef double p = 1

    cdef int i

    cdef double prod

    for i in range(n):

        p *= v[i]

    while (j < n-1):

        for i in range(n):

            v[i] -= 2*d[j]*M[j][i]

        d[j] = -d[j]

        s = -s

        prod = 1

        for i in range(n):

            prod *= v[i]

        p += s*prod

        f[0] = 0

        f[j] = f[j+1]

        f[j+1] = j+1

        j = f[0]

    return p/2**(n-1)    

Unfortunately it is still slower than just using pypy!    Looking at the output of cython -a  I see that this line

v[i] -= 2*d[j]*M[j][i]

is still being interpreted in python which I assume is what is causing the slowdown.

How can I fix that?

Raphael