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Re: pb with -ffast-math

From: Jaroslav Hajek
Subject: Re: pb with -ffast-math
Date: Fri, 17 Apr 2009 07:07:59 +0200

On Thu, Apr 16, 2009 at 9:51 PM, Alain Baeckeroot
<address@hidden> wrote:
> Le 15/04/2009 à 19:56, Jaroslav Hajek  écrit :
>> On Tue, Apr 14, 2009 at 9:54 AM, Alain Baeckeroot
>> <address@hidden> wrote:
>> >
>> > i builded octave with additional optimisation flags
> .../...
>> I use -O3 -march=native -funroll-loops and get good results.
> I'll try this.
>> > And this is really not important, i doubt we can get another 20%
>> > speed improvement.
>> Depending on your code, you may get even much better improvements by
>> switching to the development sources (it seems you use 3.0.5). An
>> instance is the experience of F. Potorti:
> Everythnig is vectorised, except one for-loop (iteration over time) which
>  takes 90% of time !
> We are going to write this short part in C in a .oct file.

Could you post the relevant piece of code? Maybe there's a vectorized
way you didn't see, or one that only works with development version,
or maybe it will be something worth a new function.


RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic

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