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1989-05-30
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265 lines
MANDELBROT MAGIC
VERSION 3.1
June 1, 1989
Version 3.1 of Mandelbrot Magic adds some new features, improves the
performance of several functions and fixes a couple of bugs. This
file describes the relevant changes and also contains additional
comments of interest. If you have Mandelbrot Magic Version 3.0, you
probably will not have to read the Version 3.1 manual if you read this
file. If you have never used Mandelbrot Magic, read the manual first;
this document is probably of little interest to you.
1. We have changed the format of both compressed and uncompressed
slide files. Instead of saving the slide as a series of columns,
Mandelbrot Magic now saves it as a series of rows. There are
several advantages to this:
o Compressed files are 10 to 30 percent smaller. Uncompressed
files remain the same size as before.
o All files load from 25 to 50 percent faster.
o When using BackMAGIC to create a slide in the background,
BackMAGIC will interrupt your work to save data less
frequently.
o The new format enabled us to greatly reduce the time it takes
to display slides.
Because of this change, files created with Version 3.1 cannot be
read by Version 3.0. However, Mandelbrot Magic 3.1 can read
Version 3.0 files and convert them into Version 3.1 files quite
easily. To do this, follow these steps:
1) Start Mandelbrot Magic Version 3.1.
2) Load the Version 3.0 file you want to convert by entering its
name and pressing F9 to load. If you try to display the slide
at this point, Mandelbrot Magic will tell you that the slide is
not completed yet.
3) Press F8 to Create the slide. Mandelbrot Magic will display
the existing slide row by row. As it displays the slide, it
converts the file into the new format. This process takes
approximately two minutes on an XT. Mandelbrot Magic will also
create a backup copy of the old slide file with the extension
".V30", e.g. "M1_EGA.PIC" becomes "M1_EGA.V30".
All of the slides distributed with this program have been
converted into the Version 3.1 file format.
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BackMAGIC Version 3.1 also uses the new file format. BackMAGIC
Version 3.1 cannot read slide files created by Mandelbrot Magic
Version 3.0. You must first convert these files into Version 3.1
files.
2. We have implemented a new slide generation algorithm which can
GREATLY reduce calculation times, especially if you are not using
a math coprocessor. This algorithm is based upon the following
concept: If you enclose an area of a slide with points have the
same iteration value, then every point within that area has the
same value. Although we do not know if this has been proved
mathematically yet, it makes sense intuitively and it generates
slides correctly (at least during our tests).
The new algorithm works by overlaying a series of successively
smaller grids on the slide. After each grid is produced, each
square of the grid is check to see if all the points on its
perimeter are equal. If so, then the entire square is filled with
that value. When the last grid is produced, Mandelbrot Magic
starts generating the slide with the normal algorithm.
This method can substantially reduce the time required to produce
a slide. Furthermore, the time savings are exponential; the
longer it takes to produce a slide, the greater the percentage
savings. Our tests indicate that this method does not save much
time on slides which can be generated in less than 20 minutes (on
an XT with an 8087). On most slides, the new method saves 20 to
40 percent. On really complex slides, the savings can be
astounding. One slide which took 27 hours to produce (with an
8087) with the standard method took just 5 hours with the new
method! Likewise, the savings when NOT using an 8087 are
impressive (often 50 to 80 percent).
In Version 3.1, you can generate a slide with or without this new
method. To use the new method, create the slide by pressing
Alt-F8. To bypass the new method, just press F8. If you want to
stop a slide, press ESC. If you are using the new method,
Mandelbrot Magic will start generating the slide with the old
method. Press ESC again if you want to stop the slide entirely
and return to the Control Panel. Note that the two methods are
interchangeable -- you can start a slide with one method, stop it,
then resume calculation with the other method.
There is one disadvantage to this new method. Mandelbrot Magic
does not save any of the slide data to disk while it is using the
new method. No data is saved until the grid process is completed
and Mandelbrot Magic starts generating the slide one row at a
time. The percent complete indicator on the screen now represents
the percentage of the slide which has been saved to disk, not the
percentage that has been calculated. Consequently, you should
probably not use this new method if you know that you will not be
able to finish the slide or at least complete a large part of it.
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Finally, please note that BackMAGIC does not use this new
methodology.
3. In addition to this shortcut method of generating slides, the
basic slide generation speed when using a math coprocessor has
been increased by 60 percent.
4. The time required to display a slide has been cut by 60 percent!
This is a much needed improvement, especially on slower machines.
It also makes the Animation (F7) technique much more impressive.
5. There was a bug in Version 3.0 of Mandelbrot Magic which prevented
it from saving (and hence loading) UNCOMPRESSED files properly on
some systems. If you created a slide without compression, you
were not be able to load and redisplay the slide. If you tried
this, you got a "Fatal Error 1" message and the program crashed.
This bug has been fixed.
6. Additional testing reveals that the compression algorithm is more
efficient than we first thought. Compressed files are almost
always 60 to 70 percent smaller than uncompressed files. More
importantly, we've discovered that they often (usually?) load
FASTER than uncompressed files.
7. The section about printing slides in the manual is incomplete. If
you have DOS 4.x, then the version of GRAPHICS.COM supplied with
DOS 4.x does support EGA and VGA printouts. If you have DOX 4.x
but are not using it, then you can allegedly patch the new
GRAPHICS.COM to work with other DOS versions. See PC Magazine,
April 25, 1989, page 315 for details. Left Coast has not tested
this patch and assumes no responsibility for the results if you
try this patch.
8. The manual fails to mention that Mandelbrot Magic is incompatible
with many screen blankers. Once the screen is blanked, your
system may freeze. Try pressing ESC then 'Y' to stop the slide
generation process and return to the Control Panel. If this
doesn't work, you will have to reboot.
This is generally not a problem while viewing a slide since you
will probably press a key often enough to keep the screen blanker
from clearing the screen. It is a problem while generating
slides, however, so you should deactivate any screen blanker while
creating a slide.
We would like to keep track of which screen blankers are and are
not compatible with Mandelbrot Magic so let us know of your
experiences in this area.
9. Several users have suggested the following as another good
book on fractals:
Barnsley, Michael. Fractals Everywhere. San Diego:
Academic Press, 1988.
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10. BackMAGIC has been modified to work only with Version 3.1 file
formats. The new version is BackMAGIC Version 3.1 rather than
Version 1.0. In the future, the version number for Mandelbrot
Magic and BackMAGIC will always correspond, even if there have
been no changes to one of the programs.
11. The Control Panel for BackMAGIC now displays the name of the slide
being created and the percentage completed.
12. When BackMAGIC is finished, it displays the name of the slide file
it just created.
13. The Zoom function is now more flexible. In EGA and VGA modes, the
Shift-Arrow keys now move the cursor by 20 pixels rather than 10.
When the crosshairs cursor is displayed, pressing Home, End, PgUp
and PgDn will move you to the respective corners of the slide.
When a Zoom box is displayed, you can make any of the four corners
the "active" corner by pressing Home, End, PgUp or PgDn. This
allows you to precisely position the Zoom box to capture any
specific detail.
14. Mandelbrot Magic now supports the extended EGA mode (640 by 480
pixels) on the Paradise Autoswitch 480 EGA card. You can choose
this mode from the Control Panel. WARNING: IF YOU TRY TO GENERATE
OR DISPLAY A SLIDE IN PARADISE MODE ON ANY OTHER EGA CARD, YOUR
SYSTEM WILL CRASH!!! This Paradise mode provides the same
resolution as the VGA and hence requires the same amount of
memory. Also, slides generated in Paradise mode can be viewed on
a computer with a VGA adapter but not vice versa.
A general note: As we add support for extended EGA and VGA modes,
Mandelbrot Magic will not automatically detect which extended
modes are supported by your video card (with the probable
exception of Super VGA). Why? Because (1) the program would get
too big and (2) many of these cards provide no way to detect their
presence. We will continue to detect the presence of CGA, EGA,
and VGA adapters, however.
15. While viewing a slide, you can now change the Number of Color
Regions prior to redisplaying a slide (with F10, Ctrl-F10,
Alt-F10, or Shift-F10) without returning to the Control Panel.
Press Alt-N to pop up a data input window. Simply enter the
number of regions and press <Return>. Press <Esc> to cancel.
16. Many users have asked if we intend to support the VGA modes which
can show 256 colors at a time. The answer is a qualified "yes".
Right now, our emphasis (based on customer requests) is on
increasing the resolution of the slides. As a result, we do not
intend to support the 320 x 200 x 256 color VGA mode in the
foreseeable future. We feel this resolution is just not adequate
for "serious" exploration. We do intend to support the Super VGA
"standard" if and when it truly becomes a standard. This will
provide 800 x 600 x 16 colors at a minimum. The next step after
that will be to provide support for a mode with more colors
(hopefully 640 x 480 x 256 or even 800 x 600 x 256).
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