Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!silver!viking
From: viking@silver.bacs.indiana.edu (Jon W. Backstrom)
Newsgroups: comp.sys.mac.programmer
Subject: Re: How to Cosine
Message-ID: <28548@iuvax.cs.indiana.edu>
Date: 27 Oct 89 12:27:48 GMT
References: <2157@hudson.acc.virginia.edu> <2143@draken.nada.kth.se> <23401@cup.portal.com>
Sender: viking@silver.bacs.indiana.edu (Jon W. Backstrom)
Reply-To: viking@silver.bacs.indiana.edu (Jon W. Backstrom)
Organization: Indiana University, Bloomington
Lines: 23

In article <23401@cup.portal.com> wetter@cup.portal.com (Pierce Wetter) writes:
>   You want to use something called a CORDIC algorithm. If I remember 
>correctly it uses shifts to do the divisions and multiplications by powers of
>two, and uses some algoritm that only requires divison and multiplication
>by powers of two. CORDIC is the name of the machine the algorithm was 
>implemented for.
>Pierce

Where is Jim Cathey when you really need him?!  :-)   Jim converted a
fractal landscape program, originally published in Creative Computing,
to use cordic rotators and the speedup is indeed amazing.  The actual
work involves multiplication by powers of two and this required only
shifting bits in the code.

As a naive programmer, not heavily into math theory, I was fascinated
to see how it worked.  Made want to learn more about math again.  (True)

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 Jon W. Backstrom                 "Yah sure...we gonna have fun, you bet!"
 Institute for Digital Arts
 P.O. Box 176                     Internet: viking@silver.bacs.indiana.edu
 Bloomington, IN  47402-0176      UUCP: {ames,rutgers,att}!iuvax!silver!viking
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