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/  
 [128.252.135.4]. 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 [128.32.150.27]. 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.