Subject: Fractint

Q22a: What is Fractint?

A22a: Fractint is a very popular freeware (not public domain) fractal generator. There are DOS, MS-Windows, OS/2, Amiga, and Unix/X-Windows versions. The DOS version is the original version, and is the most up-to-date.

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

19.6 executable via FTP and WWW from SimTel & mirrors world-wide

http://www.coast.net/cgi-bin/coast/dwn?msdos/graphics/frain196.zip

19.6 source via FTP and WWW from SimTel & mirrors world-wide

http://www.coast.net/cgi-bin/coast/dwn?msdos/graphics/frasr196.zip

19.6 executable via FTP from Canada

ftp://fractal.mta.ca/pub/spanky/programs/ibmpc/frain196.zip

19.6 source via FTP from Canada

ftp://fractal.mta.ca/pub/spanky/programs/ibmpc/frasr196.zip

(The suffix 196 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.

Windows

MS-Window FractInt 18.21 via FTP and WWW from SimTel & mirrors world-wide

http://www.coast.net/cgi-bin/coast/dwn?win3/graphics/winf1821.zip

MS-Window FractInt 18.21 via FTP from Canada

ftp://fractal.mta.ca/pub/spanky/programs/ibmpc/windows/winf1821.zip

MS-Windows FractInt 18.21 source via FTP and WWW from SimTel & mirrors world-wide

http://www.coast.net/cgi-bin/coast/dwn?win3/graphics/wins1821.zip

MS-Windows FractInt 18.21 source via FTP from Canada

ftp://fractal.mta.ca/pub/spanky/programs/ibmpc/windows/wins1821.zip

OS/2

Available on Compuserve in its GRAPHDEV forum. The files are PM*.ZIP. These files are also available on many sites, for example http://oak.oakland.edu/pub/os2/graphics/

Unix

The Unix version of FractInt, called XFractInt requires X-Windows. The current version 3.04 is based on FractInt 19.6.

3.04 source Western Canada

http://spanky.triumf.ca/pub/fractals/programs/unix/xfract304.tgz

3.04 source Atlantic Canada

http://fractal.mta.ca/spanky/programs/unix/xfract304.tgz

XFractInt is also available in LIB 4 of Compuserve's GO GRAPHDEV forum in XFRACT.ZIP.

Xmfract by Darryl House is a port of FractInt to a X/Motif multi-window interface. The current version is 1.4 which is compatible with FractInt 18.2.

README

http://fractal.mta.ca/pub/fractals/programs/unix/xmfract_1-4.readme

xmfract_1-4_tar.gz

http://fractal.mta.ca/pub/fractals/programs/unix/xmfract_1-4_tar.gz

Macintosh

There is NO Macintosh version of Fractint, although there may be several people working on a port. It is possible to run Fractint on the Macintosh if you use a PC emulator such as Insignia Software's SoftAT.

Amiga

There is an Amiga version also available:

FracInt 3.2

http://spanky.triumf.ca/pub/fractals/programs/AMIGA/

FracXtra

There is a collection of map, parameter, etc. files for FractInt, called FracXtra. It is available at

FracXtra Home Page by Dan Goldwater

http://fatmac.ee.cornell.edu/~goldwada/fracxtra.html

FracXtra via FTP and WWW from SimTel & mirrors world-wide

http://www.coast.net/cgi-bin/coast/dwn?msdos/graphics/fracxtr6.zip

FracXtra via FTP

ftp://fractal.mta.ca/pub/spanky/programs/ibmpc/fracxtr6.zip

Q22b: How does Fractint achieve its speed?

A22b: Fractint's speed (such as it is) is due to a combination of:

1. Reducing computation by Periodicity checking and guessing solid areas (especially the "lake" area).
2. Using hand-coded assembler in many places.
3. Using fixed point math rather than floating point where possible (huge improvement for non-coprocessor machine, small for 486's, moot for Pentium processors).
4. Exploiting symmetry of the fractal.
5. Detecting nearly repeating orbits, avoid useless iteration (e.g. repeatedly iterating 0²+0 etc. etc.).
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 three are probably the most important. Some of these introduce errors, usually quite acceptable.