%load_ext cythonmagic

%%cython -lcblas
import numpy as np

cdef extern:
    double  ddot_( int* N,  double*   X, int* INCX, double* Y, int* INCY )  nogil
    
cpdef double dot(double[:] a, double[:] b) nogil:
    cdef int inc = 1
    cdef int n = a.shape[0]
    
    return ddot_(&n, &a[0], &inc, &b[0], &inc)
    
def main():
    
    a = np.random.rand(100)
    b = np.random.rand(100)
    s = dot(a,b)
    

    a = np.random.rand(100)
    b = np.random.rand(100)

%timeit dot(a,b)
%timeit np.dot(a,b)