Path: chuka.playstation.co.uk!news
From: Phil Gooch <philg@easynet.co.uk>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Square Root
Date: Fri, 21 Aug 1998 16:43:46 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Alex Herbert wrote:

> OK, I know that using square roots is best avoided, and in most cases
> they can be.  But sometimes they just can't be avoided.  I decided that
> using floating point was not the way to go, but I've never seen a square
> root algorithm before, so this is what I came up with.
>
> u_short sq_root(u_long n) {
>     u_short a=0x8000;
>     u_short b=0;
>     u_short c;
>
>     while(a) {
>         c=a|b;
>         if(c*c<=n)
>             b=c;
>         a=a>>1;
>     }
>     return(b);
> }
>
> It works fine, but does anyone know a better way to find the sqaure root
> of any u_long?
>
> Herbs

I seem to remember from A level maths that there's a summation expression
(e.g. 1 + a/n + a/n2...etc) for approximating square root. Can't remember
what it is, but any standard textbook should have it.

Phil