Chris Colbert skrev:
> so moral of the story, if you have a numpy script that makes repeated
> use of pow you probably wont speed it up with cython, because pow is a
> huge bottleneck.
>
I'd go further than this:
NumPy is written in C and you should not expect replacing NumPy's C with
Cython's generated C to give you a huge performance boost. In some
situations NumPy will call high performance libraries such as MKL or
ATLAS, and chances that you can write something more efficient are slim.
There are really only two (or maybe three) situations where Cython will
help over vectorized NumPy:
- The first is creation of temporary arrays from overloaded operators.
If this is the bottleneck, Cython might help. Computation is fast,
memory access is slow.
- The second is algorithms that are iterative or recursive, but not
"data parallel":
for i in range(n):
x[n] = foobar(x[n-1])
- The third is NumPy not releasing the GIL, and restricting
multithreaded code to one CPU.
S.M.
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