Path: chuka.playstation.co.uk!news
From: Andrew Partington <andrew.partington90@ntlworld.com>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: sqrt function.
Date: Fri, 24 Oct 2003 01:15:23 +0000
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <bn9ro2$m4k24@www.netyaroze-europe.com>
References: <bn93rl$m4k21@www.netyaroze-europe.com>
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In-Reply-To: <bn93rl$m4k21@www.netyaroze-europe.com>

Hi Kenny,

Is this the sqrt() function in the standard maths lib you're talking 
about?

If so, I can't help you, but I curently use the following code for doing 
square roots, I think I may have found it on a Yaroze members website or 
on the newsgroups, but i'm not sure who the author really is.

Maybe this one will work for you - it's reputed to be quicker than the 
standard one anyway.

Cheers,

Andy P



#define STEP(k) s=r+(1L<<k*2);r>>=1;if(s<=v){v-=s;r|=(1L<<k*2);}



unsigned long    sqrt_u_32(unsigned long n)

{

     unsigned long    r=0,s,v=n;



     STEP(15);STEP(14);STEP(13);STEP(12);

     STEP(11);STEP(10);STEP(9);STEP(8);

     STEP(7);STEP(6);STEP(5);STEP(4);

     STEP(3);STEP(2);STEP(1);STEP(0);

     return r;

}

unsigned short        sqrt_u_16(unsigned short n)

{

     register unsigned short     r=0,s,v=n;



     STEP(7);STEP(6);STEP(5);STEP(4);

     STEP(3);STEP(2);STEP(1);STEP(0);

     return r;

}


Kenny Millar wrote:
> Hi all,
> 
> I finally got my build environment to work under XP Pro.
> 
> However, using FCC 2.8.1 - whenever I use the sqrt function the PSX hangs
> completly.
> 
> even just doing this....
> 
> x=sqrt(16);
> 
> hangs the console.
> 
> Anyone else using sqrt having this trouble?
> 
> -Kenny
> 
>