gistfile1.py

from cpython cimport PyCObject_AsVoidPtr
from scipy.linalg.blas import fblas

from libc.math cimport fabs

ctypedef float (*sdot_ptr) (const int *N, const float *X, const int *incX, const float *Y, const int *incY) nogil
cdef sdot_ptr sdot=<sdot_ptr>PyCObject_AsVoidPtr(fblas.sdot._cpointer)

ctypedef double (*dsdot_ptr) (const int *N, const float *X, const int *incX, const float *Y, const int *incY) nogil
cdef dsdot_ptr dsdot=<dsdot_ptr>PyCObject_AsVoidPtr(fblas.sdot._cpointer)

cdef int ONE = 1

cdef double test_dsdot(int what) nogil:
    cdef float *x = [10.0]
    cdef float *y = [0.01]
    cdef float expected = 0.1
    cdef int size = 1
    cdef double d_res
    cdef float *p_res

    d_res = dsdot(&size, x, &ONE, y, &ONE)
    p_res = <float *>&d_res
    if (what == 0):
        return d_res
    if (what == 1):
        return p_res[0]
    if (what == 2):
        return p_res[1]
    return sdot(&size, x, &ONE, y, &ONE)

print 'double', test_dsdot(0)
print 'float[0]', test_dsdot(1)
print 'float[1]', test_dsdot(2)
print 'float', test_dsdot(3)