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Q21a: What is Fractint? A21a: Fractint is a very popular freeware (not public domain) fractal generator. There are DOS, Windows, OS/2, and Unix/X versions. The DOS version is the original version, and is the most up-to-date. There is a new Amiga version. Please note: sci.fractals is not a product support newsgroup for Fractint. Bugs in Fractint/Xfractint should usually go to the authors rather than being posted. Fractint is on many ftp sites. For example: DOS: ftp from ftp://wuarchive.wustl.edu/systems/ibmpc/simtel/ [126.96.36.199]. The source is in the file frasr182.zip. The executable is in the file frain182.zip. (The suffix 182 will change as new versions are released.) Fractint is available on Compuserve: GO GRAPHDEV and look for FRAINT.EXE and FRASRC.EXE in LIB 4. There is a collection of map, parameter, etc. files for Fractint, called FracXtra. Ftp from ftp://wuarchive.wustl.edu/systems/ibmpc/simtel/. File is fracxtr5.zip. Windows: ftp to ftp://wuarchive.wustl.edu/systems/ibmpc/simtel/ . The source is in the file wins1821.zip. The executable is in the file winf1821.zip. OS/2: available on Compuserve in its GRAPHDEV forum. The files are PM*.ZIP. These files are also available by ftp: ftp://ftp-os2.nmsu.edu/pub/os2/2.0/ in pmfra2.zip. Unix: ftp to sprite.berkeley.edu [188.8.131.52]. The source is in the file xfract203.shar.Z. Note: sprite is an unreliable machine; if you can't connect to it, try again in a few hours, or try hijack.berkeley.edu. Xfractint is also available in LIB 4 of Compuserve's GO GRAPHDEV forum in XFRACT.ZIP. Macintosh: there is no Macintosh version of Fractint, although there are several people working on a port. It is possible to run Fractint on the Macintosh if you use Insignia Software's SoftAT, which is a PC AT emulator. Amiga: There is an Amiga version at ftp://wuarchive.wustl.edu/pub/aminet/gfx/ . For European users, these files are available from ftp.uni-koeln.de. If you can't use ftp, see the mail server information below. Q21b: How does Fractint achieve its speed? A21b: Fractint's speed (such as it is) is due to a combination of: 1. Using fixed point math rather than floating point where possible (huge improvement for non-coprocessor machine, small for 486's). 2. Exploiting symmetry of the fractal. 3. Detecting nearly repeating orbits, avoid useless iteration (e.g. repeatedly iterating 0^2+0 etc. etc.). 4. Reducing computation by guessing solid areas (especially the "lake" area). 5. Using hand-coded assembler in many places. 6. Obtaining both sin and cos from one 387 math coprocessor instruction. 7. Using good direct memory graphics writing in 256-color modes. The first four are probably the most important. Some of these introduce errors, usually quite acceptable.