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@johnmyleswhite
Last active August 10, 2018 10:58
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Naively counting Pythagorean triples in Python and Julia
total = 0
N = 300
start_time = time()
for a in 0:(N - 1)
for b in 0:(N - 1)
for c in 0:(N - 1)
if a^2 + b^2 == c^2
total = total + 1
end
end
end
end
end_time = time()
end_time - start_time
# Repeat now that JIT has done its work
total = 0
N = 300
start_time = time()
for a in 0:(N - 1)
for b in 0:(N - 1)
for c in 0:(N - 1)
if a^2 + b^2 == c^2
total = total + 1
end
end
end
end
end_time = time()
println(end_time - start_time)
function loop(N::Integer)
total = 0
start_time = time()
for a in 0:(N - 1)
for b in 0:(N - 1)
for c in 0:(N - 1)
if a^2 + b^2 == c^2
total = total + 1
end
end
end
end
end_time = time()
return end_time - start_time
end
loop(300)
# Repeat now that JIT has done its work
println(loop(300))
total = 0
N = 300
from time import time
start = time()
for a in range(N):
for b in range(N):
for c in range(N):
if a**2 + b**2 == c**2:
total = total + 1
end = time()
print(end - start)
@seanjtaylor
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Under PyPy I got a mean of 45ms over 100 runs, also on a recent Macbook Pro. 4.5x faster than the PyPy JIT is pretty awesome.

@vgoklani
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Using cython via ipython notebook:
%load_ext cythonmagic

paste this into the next cell block:

%%cython
import numpy as np

cimport numpy as np
cimport cython

@cython.boundscheck(False)
@cython.wraparound(False)
cpdef calc(N=300):
    cdef:
        np.int total = 0
        Py_ssize_t i, j, k
    for i in xrange(N):
        for j in xrange(N):
            for k in xrange(N):
                if i**2 + j**2 == k**2:
                    total = total + 1
    return total

paste this into the next cell block:
%timeit -n3 calc()

3 loops, best of 3: 19.1 ms per loop

@diegozea
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diegozea commented Jun 7, 2013

If N is defined as const in JuliaGlobals, the time changes from 660 ms to 34 ms on my machine

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