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Hottest 6 (1996)(PDSoft)[!].iso
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mandelbrot.readme
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1978-11-24
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Mandelbrot & Julia Fractals
About:
This is a little program i wrote for fun, and now I decided to complete
it and make it system friendly (no direct BitMap writes, etc.) and
copy it around.
Read the window on the program's screen for instructions and play around.
The Mandelbrot-pattern is a wonderful thing to explore, that's why I
made this program..
All three windows can be closed, they can be reopened by hitting I, C or A.
Click in the picture to magnify around that spot.
The Control window contains the Gadgets for selecting Julia fractals.
You can change iterations, magnify, or change fractal before rendering
finishes. The program will restart rendering.
Internas & multitasking
Note that the program works with 32-bit numbers. If you zoom in too
much (30 clicks, magnified about *1000000000), the picture will become
chunky, then the screen will turn blank.
The program does not crash, but its range is exeeded.
(A 64-bit version could help, but would be much slower.)
All the calculation is performed in a low priority subtask. If any other
higher priority task is running full time (without ever calling EXEC/wait)
this program's subtask will not get any more CPU time from the operating
system. Stop these tasks or reduce their priority below -25.
For example, games like Microprose's Railroad tycoon poll for key inputs
instead of waiting for them, wasting system time.
You may even get problems quitting, because the program will wait for the
subtask to quit before quitting itself.
Copyright
There is no copyright on this. Just don't try to claim this your work...
Screen resolution
I don't know how to program a screen mode requester, therefore i supplied
a LoRes and a HiRes version of the program.
System requirements
The Program requires a 68020 or better processor to run, since it uses the
instructions 'muls.l' and 'mulu.l'. I think a 68000 version would be too
slow, so I did not bother making one.
The program should run on >any< Amiga with at least a 68020 processor and
any revision of the operating system, but if you encounter any problems,
please let me know.
I tested it on the Amiga 4000/040 and the Amiga 1200 (68020),
both running Kickstart 39.106 and WB 3.0
Speed
The use of system routines for graphics output reduces the speed a little,
but most of the working time is used for the iteration.
The recursive algorithm greatly increases speed compared to pixel-by-pixel
calculation, but the more you magnify and increase iteration depth, the
longer it will take to render a frame.
Rendering the first picture of the Mandelbrot fractal in low resolution took
3.5 seconds on the Amiga 4000/040,
12 seconds on the Amiga 1200 with fastRAM and
15 seconds on the Amiga 1200 with fastRAM disabled.
The sample picture supplied with the archive took about 56 seconds to render
(68040/25MHz, LoRes, 1368 Iterations)
Achim Dahlhoff
Aachen, germany
email: DAHLHOF@reze-1.rz.rwth-aachen.de