1 Overview.txt =TITLE Overview Yadman (Yet Another Damn MANdelbrot program) can generate and display images of the Mandelbrot set. The Mandelbrot set is produces images of fractals, fractional dimensions, that are pleasing to the eye. Fractals are self-similar. That is, when you zoom in on a section, it appears similar, but different to the larger view. Coastlines are fractal, it is hard to tell whether you are looking at a few miles or a few hundred miles of coastline. Most of the following doesn't matter when you use the program, just go ahead and enjoy. The Mandelbrot set is a set of points laying on the complex plane. The complex plane comprises Real numbers in the X dimension and Imaginary numbers in the Y dimension (unless I have it backwards). A point is in the Mandelbrot set if you perform a certain calculation and the result is infinity. Here we approximate the calculation and assign a color to each point that represents "how quickly it is fleeing the set". In other words, the points you see are not in the Mandelbrot set, but close to it. Computing the image can be very time consuming, as each point must be examined in turn. Please keep that in mind when choosing areas to view. For more information on the Mandelbrot set, please refer to the Computer Recreations column in the following Scientific Americans: August 1985, November 1987, and February 1989. 2 hints =TITLE Hints The defaults produce an overview of the entire Mandelbrot set. Use the NEW function and the LAUNCH command to generate new views. Once you have an image on the screen you can select an area of interest with the mouse (by pressing the large rectangular button in the NEW box) and LAUNCHing that area. An image of 400 pixels with an iteration of 100 is computable in a reasonable amount of time even on a .9 VUP machine. The larger the number of pixels and the more iterations, the longer it can take. I recommend a DECstation 3100 to really have fun with this program. It can generate an 800 pixel image with 250 colors in only a few minutes. You can achieve a wide range of special effects by playing with the values in the COLOR OPTIONS box. 2 file =TITLE File These are the usual file options, please see the DECwindows Users Guide for more details. 3 new =TITLE New Use the NEW option to generate new images. You may enter values by hand, or if an image is already on the screen, use the mouse to select a sub-region to examine. The parameters are: X (Real) The horizontal direction Y (Imaginary) The vertical direction Length The distance in the set Pixels The size of the image on the screen Iterations The number of times the algorithm tries before giving up on a point Iterations effectively defines the number of colors you will see, up to the maximum of your display (usually 16 or 256). Different iterations may produce radically different pictures. You may discover that an apparently empty region is filled if you use more iterations. If an image is already displayed you may press the large rectangular button to use the mouse to select an area. The values will automatically show up in the the correct fields. If you type in a number it does not take effect until you press APPLY. Pressing RESET brings back the previous numbers. LAUNCH causes the image to be generated. It is identical to the LAUNCH under the COMMANDS menu. Please see that section of help for more details. 3 open =TITLE Open OPEN is used to read existing files. A data file may have just the parameters, or the entire image. If it has the entire image, then the image is displayed. If it does not, then the window remains blank and you must press the LAUNCH button to view the image. 3 save =TITLE Save SAVE allows you to save your image, or just your parameters. If the image exists, it will be saved, otherwise just the parameters will be saved. 3 save_as =TITLE Save As SAVE_AS allows you to save your image under a different name. 3 exit =TITLE Exit EXIT causes the application to finish. If you have generated an image and not yet saved it, you are given the option of saving the image before you exit. 2 commands =TITLE Commands The options under the COMMANDS menu cause actions to take place. 3 launch =TITLE Launch LAUNCH causes the image to be generated. This can be very time consuming. Even a small 400 pixel image with 100 iterations can take more than 10 minutes on a slow machines. An 800 pixel, 250 iteration image may take an hour or more. Of course on a DECstation 3100, it takes just a few minutes. A generation may be cancelled by pressing the cancel button that appears during the launch. I find it convenient to examine areas with small sizes and small iterations and then when I find an area of interest, generate it at lunch time with a larger number of pixels and iterations. 3 animate =TITLE Animate ANIMATE manipulates the color map to cause visual effects approximating those seen daily by inhabitants of the west coast. 3 brain_fade =TITLE Brain Fade BRAIN FADE is another animation sequence. It is sometime hard to differentiate between this command and simply 20 hours of non-stop programming. 2 options =TITLE Options OPTIONS gives you the ability to manipulate the image on the screen. 3 colors =TITLE Colors The COLORS option gives you the ability to create many dazzling visual effectives. By changing the values of the three numbers you effect how numbers are stored in the color map. You may type numbers directly, or use the icons to move them up and down by the selected increment. Numbers that you type in do not become effective until you press the APPLY button. Pressing RESET allows brings back the default numbers. You may choose between SHIFT and MULTIPLY for different effects. The former shifts the color map entries by the shown factor, and the later multiplies them. If you really care how it's done, read the source code. Otherwise, just enjoy. 3 auto_resize =TITLE Auto Resize Selecting AUTO RESIZE causes the window to automatically assume the same size as the image. Selecting NO AUTO RESIZE causes the window to stay the same size and allows you to scroll around the image. You may also resize the window at any time by using the standard DECwindows resize button. Please refer to the DECwindows Users Guide for more details.