Re: [Mingw-users] Re[2]: MinGW 3.0.0 pow function is 10x slower than 2.0.0

[<dan...@ya...>]

 --- W Menn <wi...@ho...> wrote: > Danny,
> 
> Thanks again for your helpful responses.  Okay, I'm a little slow here, but 
> I take it that the 64-bit mantissas are only used for locally stored 
> (register) variables and for internal math ops, but that stored doubles 
> still take up 8-bytes and have a 53-bit mantissa.  Correct?  That would be 
> why --float-store fixes the problem, no?
> 
Like that.  The x = pow(z,y); k= (int)x is probably were the float storage is needed. with optima

> Anyway, I don't really care about the pow(int,int) problem rounding down 
> incorrectly in certain cases.  That was somebody elses bug (and a very minor 
> one to me--if I wanted the correct integer result, I'd add 0.5 to the value 
> before converting to int).  What I do care about is that the default pow 
> function for mingw compiles is now the 10x slower one (I make my bread and 
> butter by my numerical codes running quickly).  Do you plan to change that 
> in a future release based on our recent exchange?
> 

I'll make some change that gets the speed up, unless someone beats me to it.
Danny 

> -Willus
> 
> 
> From: Danny Smith <dannysmith@cl...>
> Re: Re: MinGW 3.0.0 pow function is 10x slower than 2.0.0
> 2003-09-23 14:47
> 
> By calling this at startup:
> 
> /*
>   * CRT_FP10.c
>   *
>   * This defines _fpreset as asm ("fnint"). Calls to _fpreset
>   * will set default floating point precesion to 64-bit mantissa
>   * at app startup.
>   *
>   * Linking in CRT_FP10.o before libmingw.a will override the definition
>   * set in CRT_FP8.o.
>   */
> 
> /* Override library  _fpreset() with asm fninit */
> void _fpreset (void)
>    { __asm__ ( "fninit" ) ;}
> 
> void __attribute__ ((alias ("_fpreset"))) fpreset(void);
> 
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