Newsgroups: comp.sys.amiga.graphics
Path: utzoo!utgpu!watserv1!watdragon!rose!ccplumb
From: ccplumb@rose.uwaterloo.ca (Colin Plumb)
Subject: Re: Mandelbrot Madness
Message-ID: <1991Jan29.050043.4019@watdragon.waterloo.edu>
Keywords: Mandelbrot
Sender: daemon@watdragon.waterloo.edu (Owner of Many System Processes)
Organization: University of Waterloo
References: <1991Jan11.233512.1@vax1.mankato.msus.edu> <18834185.ARN09718@prolix.ccadfa.oz.au> <NAPO.91Jan12233534@elektra.hut.fi> <188483a4.ARN09773@prolix.ccadfa.oz.au> <1991Jan27.074838.10517@watdragon.waterloo.edu> <18986df1.ARN27d8@prolix.ccadfa.oz.au>
Date: Tue, 29 Jan 91 05:00:43 GMT
Lines: 46

ccadfa.cc.adfa.oz.au!prolix!dac@munnari.OZ.AU wrote:
>In article <1991Jan27.074838.10517@watdragon.waterloo.edu>, Colin Plumb writes:
>> Wimp.  It is a fact of life that, however much processing speed you have,
>> you're always going to start generating pictures that take over 20 minutes.

>Is this some 'aha' experience speaking, or a general truism that you've decided
>to espouse without using anything firm like facts? :-)

It was something we concluded, based on a magazine article somewhere
(we were looking up neat mandelbrot spots) that asserted that the
comfortable computation time was one coffee break.  It's an observation
based on playing with mandelbrot exploration programs.

>> Of course, the last Mandelbrot demo I wrote was for a 28-processor transputer
>> system, so I had it in places where 15,000 iterations was too fuzzy; I had
>> to go to 17,000.  At 513x513 resolution, this wrapped the flops counter
>> past 2^32.
>
>Right. (512^2) * 17000 = 4.4*10^12 flops. 
>
>Therefore you are saying that you were doing a screen a second? (what's 'a'
>flops, hmm?). A 4Gflops machine is very bloody fast.

No, by "flops" I meant "floating point operations", not per second.
16,000 iterations (2^14) average times slightly over 2^18 pixels
produces 2^32 z^2+c iterations total (which was what I was actually
counting).  I used this figure to print an average computation speed
for the picture.  I remember getting 4 million mandelbrot iterations a
second, so we're talking 1,000 seconds, which equals 16 2/3 minutes.
We actually got up to half an hour or so.

>> Really, there are some great spots I couldn't find with lower iteration
>> levels around n=5,000.
>
>Madness.  Sheer madness.  The TV special 'Chaos' had some pretty spiffy
>Mandebrot animations, that looked real-time (just going down seahorse valley,
>seemingly forever).  I did n=4000 on MandFXP, and it just took AGES (this was
>in a window about 50 pixels by 20 pixels!).

I was just trying to illustrate that it's *never* fast enough.  I'd like
to get a bunch of the BIT 100 MFLOPS floating-point ALU's and build
a hardware z^2+c toy.  It would cost a few thousand dollars, but give
you 100 million Mandelbrot iterations a second.  But I'd still manage to
run out...
-- 
	-Colin
