(User.programs)
Item: 224 by _ciarn at hpcvbbs.UUCP
Author: [Dan Ciarniello]
  Subj: Mandelbrot Sets
  Keyw: fractals mandelbrot
  Date: Sun Feb 10 1991

FRACTALS.SRC contains commented source code.  FRACTALS is the binary version to
be downloaded to your 48.  It also includes four sample fractal images (in F1,
F2, F3, and F4).

The custom menu contains the programs that are accessed directly by the user.
All other programs are called by 'MANDEL.'

To generate fractal images:

1.  Enter the coordinates of the lower left and upper right corners of the
    desired window (as complex numbers) in levels 1 and 2 respectively.  Note
    that the entire Mandelbrot set is contained in the window (-2,-1) (1.5,1).  
2.  If dithering is desired, press 'DITH' otherwise press 'NODITH.' You can
    tell whether dithering is on by checking flag 3.  (Dithering simply adds
    features to the region outside of the Mandelbrot set.)
3.  Press 'MAND.'

Random Notes:

You can follow progress by watching for the pixel which briefly toggles on and
off.  'nITTR' contains the maximum number of iterations that 'ITERATE' will do
before 'bailing out.' It has a default value of 100 which you change.  The
entire Mandelbrot set will take about 1 hour 15 minutes to generate (for
nITTR=100; subsets will take longer).  The program returns a value representing
the number of hours taken to generate the image to stack level 1.  The rest of
the stack is left intact.  The algorithm used to generate the image makes some
neat patterns as it progresses.  I get a kick just watching the image being
generated.

**********************************************************************
Dan Ciarniello              Dan_Ciarniello@cc.sfu.ca
Capilano College            n1n8@cc.sfu.ca
North Vancouver, B. C.      akcs.ciarn

"F=ma but you can't push a rope"

[Note: See Dan's notes in FRACTALS.SRC.   -jkh-]