Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: Nick <Nick_Porcino@bc.sympatico.ca>
Newsgroups: scee.yaroze.beginners
Subject: Re: I can'tuse math functions!!!!
Date: Wed, 01 Apr 1998 23:47:31 -0800
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Here's an alternative to a 64k table:


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

u_long Sqrt(u_long n)
{
        u_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;
}

It works fine for fixed point as long as you remember where your fixed
point belongs. In other words, if you're taking the root of a 16.16
number, shift the result left by 8 to renormalize it.

- nick