[SciPy-User] Speed-up simple function

[Nicolau Werneck]

Great suggestion. I have tried just modifying the original numpy
expression replacing the S**1.5 for S*sqrt(S), and just by doing that
I already got a 2x speedup.

In the Cython version, using S*sqrt(S) gives a 7.3 speedup. Much
better than using exponentiation. Using the approximate rsqrt will
probably bring that closer to 10x.

++nic



On Mon, Jan 10, 2011 at 10:30:57AM -0700, Charles R Harris wrote:
>    On Mon, Jan 10, 2011 at 10:22 AM, Nicolau Werneck <nwerneck at gmail.com>
>    wrote:
> 
>      That is one excellent suggestion, using multiple cores is probably the
>      best thing to do. I have tried a basic Cython implementation (because
>      it's such a basic and interesting problem), but I couldn't yet reach a
>      speedup of even 2.0.
> 
>      The big villain in the expression is the 'S**1.5'. Removing that from
>      my Cython code gives a 12x speedup. Avoiding that exponentiation can
>      be probably beneficial to other techniques too...
> 
>    The square root itself should be fast so I suspect that a log is being
>    used. What happens if you use S*sqrt(S) instead?
> 
>    <snip>
> 
>    Chuck

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Nicolau Werneck <nwerneck at gmail.com>          C3CF E29F 5350 5DAA 3705
http://www.lti.pcs.usp.br/~nwerneck           7B9E D6C4 37BB DA64 6F15
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