In [1]:

    

%load_ext cythonmagic


    

In [2]:

    

import math

def py_great_circle(lon1, lat1, lon2, lat2):
    radius = 6371 #km
    x = math.pi/180.0

    a = (90.0-lat1)*(x)
    b = (90.0-lat2)*(x)
    theta = (lon2-lon1)*(x)
    c = math.acos((math.cos(a)*math.cos(b)) +
                  (math.sin(a)*math.sin(b)*math.cos(theta)))
    return radius*c


    

In [3]:

    

%timeit py_great_circle(-72.345, 34.323, -61.823, 54.826)


    

    




1000000 loops, best of 3: 1 µs per loop

In [12]:

    

%%cython

cdef extern from "math.h":
    float cosf(float theta)
    float sinf(float theta)
    float acosf(float theta)

def great_circle(float lon1, float lat1, float lon2, float lat2):
    cdef float radius = 6371 #km
    cdef float x = 3.14159/180.0
    cdef float a, b, c, theta

    a = (90.0-lat1)*(x)
    b = (90.0-lat2)*(x)
    theta = (lon2-lon1)*(x)
    c = acosf((cosf(a)*cosf(b)) +
                  (sinf(a)*sinf(b)*cosf(theta)))
    return radius*c


    

In [13]:

    

%timeit great_circle(-72.345, 34.323, -61.823, 54.826)


    

    




10000000 loops, best of 3: 156 ns per loop

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