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FRACTRAC
Version 1.0
Copyright Bourbaki, Inc. 1991
(208)342-5849
INTRODUCTION
============
FracTrac is designed to graphically demonstrate what happens in the iterative
and recursive process of generating a fractal image in the Mandelbrot Set. It
presents a fascinating look at the interim steps associated with processing a
pixel, or a "track" of pixels. FracTrac also can be used as a "Julia" image
explorer, providing the ability to preview a Julia image from any point in the
set. Header files (.IMG) can be saved from the points to generate the actual
images in FracTools.
OPTIONAL INSTALLATION
=====================
FracTrac does not require installation. It can be run from the CD.
However, to install it on a hard disk:
* Create a directory on your hard disk - e.g. MD C:\FRACTRAC
* Change into the \FRACTRAC directory on the CD
* Type COPY *.* C:\FRACTRAC - and press <Enter>
RUNNING the PROGRAM
===================
To run FracTrac from the floppy:
* Change into the \FRACTRAC directory on the CD
* Type FRACTRAC and press <Enter>
If you installed it, to run the program from the hard disk:
- Change into the FRACTRAC directory - e.g. CD C:\FRACTRAC
- Type FRACTRAC and press <Enter>
To run the DEMOS:
- Enter any of the batch file (.BAT) names on the command line
- Press <Enter>
The VGA_xx.BAT demos run in 640x480 resolution mode. The 10X7_xx.BAT demo
runs in 1024x768 resolution mode.
Note - FracTrac defaults to running in 640x480 - 16 color VGA mode. You can
specify other video modes with the following commands:
FRACTRAC /E - Will force video to EGA 640x350 - 16 color mode
FRACTRAC /X - Will attempt to run in the highest resolution 16
color mode supported by your hardware
When FracTrac comes up, it will display an outline of the Mandelbrot Set.
FRACTRAC OPERATIONS
===================
FracTrac is designed to generate the orbits of convergence, or divergence, for
successive values of Z when iterated through the Mandelbrot equation - Z^2 + C.
Orbits can be generated for individual POINTS, or for TRACKS of points.
To generate an ORBIT for a SINGLE POINT:
- Position the mouse cursor somewhere on the screen
- DOUBLE CLICK the LEFT mouse button
This will generate a "line drawing" graph of the interim coordinates resulting
from each iteration through the equation. When the operation is complete, a
message will be displayed indicating whether the point in IN or OUTSIDE of the
set. The MAXIMUM ITERATION LIMIT, (which defaults to 256), the ACTUAL ITERATION
COUNT, and the coordinates of the point will also be displayed in the upper
left hand corner of the screen.
Points OUTSIDE the Set are divergent, meaning that the point values get
typically get bigger as the function is iterated. Points INSIDE the Set are
convergent, meaning that the point values get typically get smaller as the
function is iterated. Around the edge of the Set, points and trace lines may
appear to "oscillate," getting neither bigger or smaller. You can increase the
MAXIMUM ITERATION LIMIT by pressing the GRAY <+> key to see which way it goes.
You will notice that small differences in the starting coordinates can make
big differences in the orbits. Try using the <Arrow> keys and pressing
<Enter> to make small changes and generate orbits.
Selecting another point will clear the screen and generate a new orbit. See
the ADDITIONAL OPERATIONS and OPTIONS section for information on generating
orbits for MULTIPLE SINGLE Points - the <F2> toggle.
Note - The most interesting orbits will be generated from points close to, on
the outline of, or within the set.
To generate an ORBIT for a TRACK of POINTS:
- Position the mouse cursor somewhere on the screen
- Click the LEFT mouse button ONCE
- Drag the mouse to a new point
- Click the LEFT mouse button ONCE
This will draw a line between the two points. You can continue to draw
additional lines by dragging the mouse and clicking the Left button.
To GENERATE the ORBITS for ALL the POINTS along the TRACK:
- DOUBLE CLICK the LEFT mouse button
Sit back and watch the show...
See the ADDITIONAL OPERATIONS and OPTIONS section for information on toggling
the TRACK LINE Display On and Off - the <Ctrl T> toggle.
To STOP the GENERATION PROCESS at any time:
- Press <Esc>, or click the Right Mouse Button
To CLEAR the SCREEN to begin again:
- Press <Esc>, or click the Right Mouse Button - while nothing is
happening
To EXIT FracTrac at any time:
- Press <Alt Q>
ADDITIONAL FRACTRAC OPERATIONS and OPTIONS
==========================================
FracTrac provides a variety of additional options and features that are
implemented using the FUNCTION Keys and other keys on the keyboard. A brief
description of each of these options follows this summary.
<F1> - Toggles Display of HELP and FUNCTION Key menu
<F2> - Toggles SINGLE vs. MULTI Point Mode - On and Off
<F3> - Regenerates Last Track - mirrored on the X axis
<F4> - Regenerates Last Track - mirrored on the Y axis
<F5> - Toggles Set Outline and Axis - On and Off
<F6> - Toggles Color Plot option - On and Off
<F7> - Save Track data as a .VEC file
<F8> - Load Track file - .VEC file
<F9> - Generate a Preview of a Julia image from a single point
<F10> - Save Julia HEADER (.IMG) file
<Ctrl S> - Toggles STEP mode - On and Off
<Ctrl T> - Toggles TRACK LINE display - On and Off
<Insert> - Toggle Red Trace Lines - On and Off
<SpaceBar> - Toggles Pause when generating Tracks
GRAY <-> - Divides Current Iteration Limit by 2 (to minimum = 256)
GRAY <+> - Multiplies Current Iteration Limit by 2
<=> - Resets Iteration Limit to 256
<Up Arrow> - Move Mouse 1 pixel up
<Down Arrow> - Move Mouse 1 pixel down
<Left Arrow> - Move Mouse 1 pixel left
<Right Arrow> - Move Mouse 1 pixel right
<Home> - Move Mouse 1 pixel diagonally towards upper left
<PgDn> - Move Mouse 1 pixel diagonally towards lower right
<PgUp> - Move Mouse 1 pixel diagonally towards upper right
<End> - Move Mouse 1 pixel diagonally towards lower left
<Enter> - Accept current Mouse location and process it
OPERATION DESCRIPTIONS
======================
<F1> toggles Help menu and Function Key options On and Off. Use the cursor
control keys to scroll through the help text.
<F2> toggles the SINGLE vs. MULTI Point Mode On and Off. This option enables
you to generate and display multiple SINGLE POINT orbits, without clearing the
screen after each point. Press <Esc> or click the Right Mouse button to clear
the screen and begin again.
<F3> will regenerate the LAST Track that you drew, mirroring it on the X axis.
The first time you press <F3> it toggles the "mirror." Press <F3> again to
begin generating the orbits.
<F4> will regenerate the LAST Track that you drew, mirroring it on the Y axis.
The first time you press <F4> it toggles the "mirror." Press <F4> again to
begin generating the orbits.
<F5> toggles the Mandelbrot Set Outline and Axis display On and Off. This
enables you to generate orbits without on a "clean" black background.
<F6> toggles Color Plot option On and Off. If the option is On, the points
will be plotted in different colors.
<F7> enables you to Save an interesting Track as a data (.VEC) file. When
selected, you will be prompted to enter a filename. The Track files can then
be loaded and "replayed" using the <F8> Load Track option. Track files can
also be loaded on the command line with FRACTRAC (e.g. FRACTRAC DEMO.VEC) to
execute automatically. The .VEC extension must be specified. This is how the
demo batch files are set up.
<F8> enables you to Load and Replay a previously saved Track (.VEC) file.
Note - It is important that you LOAD .VEC files in the same resolution mode
that you SAVED them in.
<F9> generates a Preview of a Julia image from a single point selected from
the set. It will be displayed in the lower left corner of the screen.
<F10> enables you to Save a Julia HEADER (.IMG) file that can be loaded and
generated as a full screen image in FracTools.
<Ctrl S> toggles the TRACK PAUSE On and Off. The Step mode enables you to
stop and restart the generation of an orbits along a track.
<Ctrl T> toggles the TRACK LINE display On and Off. This option is used to
specify whether or not the actual Track Line you drew is redrawn when the
orbits along the Track are generated. The default is On.
<Insert> toggles the display of the orbit Trace Lines On and Off. The default
is On, which results in the "red" lines being displayed, as connecting lines,
when orbits are generated. With it Off, only the "points" are generated and
displayed.
A LITTLE BACKGROUND
===================
The term "fractal" was coined by Benoit Mandelbrot to describe the family of
shapes necessary to illustrate the irregular non-Euclidian geometry of nature.
Dr. Mandelbrot pointed out that the "geometry of nature" does not seen to be
made up of the circles, triangles, and rectangles of the ancient Greek
mathematicians.
Fractals are pure mathematical entities. They are "plotted" in a two
dimensional plane, in an X-Y Coordinate system where each individual pixel has
an X and Y value. It is also important to note that the Mandelbrot Set exists
very close to the intersection of the X and Y axis. The X values range from
approximately -2.0 to +1.0, and the Y values range from -1.2 to +1.2. The
coordinates of each pixel provide the starting values for iterative recursive
process that results in pixels being assigned colors, which in turn results in
colored regions in an image. The simple Mandelbrot equation Z^2 + C does it
all.
After each pass through the equation the "norm" of the resulting values is
checked to see if it is greater than "4." The result will either converge or
diverge. Convergence means that the result gets smaller and smaller,
approaching zero, after each iteration. Divergence means that the result gets
bigger and bigger. If the result is bigger than "4" we know it is divergent,
at which point processing stops and the pixel is assigned a color.
This is what happens in the process of generating a fractal image, pixel by
pixel. However, FracTrac does not generate fractals. It is designed to
illustrate the convergent or divergent quality of an individual pixel, or
pixels along a "track" of pixels.
CONTACT INFORMATION
===================
For additional information on Bourbaki's products, or to order, call
(800)289-1347 For technical support, call (208)342-5849.
Bourbaki, Inc. / 475 Main St. / P.O. Box 2867 / Boise, ID 83701 FracShow - Version 2.0