Path: chuka.playstation.co.uk!news
From: Alex Herbert <aherbert@ndirect.co.uk>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Square Root
Date: Fri, 21 Aug 1998 19:31:21 +0000
Organization: PlayStation Net Yaroze (SCEE)
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References: <35DD914A.BBA25235@ndirect.co.uk> <35DD9B1E.3FEAA1E5@scee.sony.co.uk> <35DDAD74.CBCD107B@hinge.mistral.co.uk>
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Craig Graham wrote:

> Alternatively, if all you want is the length of a vector,
> the manhattan distance approximation:
>
> inline short manhatan_distance(register unsigned short a,
>         register unsigned short b,
>         register unsigned short c)
> {
>  register short t;
>
>  if(a<b)    // a is > b
>  {
>   t=a;
>   a=b;
>   b=t;
>  }
>
>  if(b<c)    // b is > c
>  {
>   t=b;
>   b=c;
>   c=t;
>  }
>
>  if(a<b)    // a is > b
>  {
>   t=a;
>   a=b;
>   b=t;
>  }
>
> // t=a + (b>>2) + (c>>2);    // faster lower accuracy
>  t=a + ((11*b)>>5) + (c>>2);    // slower, more accurate
>
>  return t;
> }


Thanks for that Craig.  Not what I was looking for, but I think I'll
find this very useful.

Herbs