Compiler details

The program is written in BASIC. The source code and the executable program is available here . Due to many comment lines, the source code should be understandable for anybody with some experience in programming.  

Parameters can be changed in the code. For instance, by changing DA the diffusion rate of the activator is altered. To change the program a compiler is required that translates the changed source code into a new executable program. A shareware version of PowerBasic, ‘FirstBas’, is sufficient for this short program.  The program can also be compiled with Microsoft BASIC QB 4.5, QBX 7.1 or PowerBasic 3.5 for DOS.

More recently with FREEBASIC a BASIC-Compiler for Windows and LINUX became available. The compiler is to a very high degree compatible with QBX and POWERBASIC and freely available in the Web. The program given on the preceding page is compatible with FREEBASIC 0.20. By cut and paste the program can be copied to an editor and subsequently compiled.

Programs that allow simulations for diverse biological situation such as patterning an sea shells, phyllotaxis, gene activation, formation of net-like structures and regeneration in hydra are available on a CD accompanying the book "The Algorithmic Beauty of Sea Shells" ; Springer Verlag, Heidelberg). The programs allow also simulations in two-dimensional fields and to change parameters during a session.


Instructions to use the FreeBasic Compiler

The compiler FeeBasic is freely available form the web:
The program on the preceding page can compiled with the version 0.20.
The compiler command has to be as follows:
[path\]fbc programname[.bas] -lang qb -ex

Thus, first the path to the compiler and the name of the compiler has to be provided, for instance
The programname is as given, for instance, PATTERN[.bas]
The option
-lang qb makes the language compatible to the rules of Microsoft Basic;
-ex is required for exception handling, e.g., to react appropriate if an error occurred, for instance, if an attempt is made to read a file that does not exist (caution: if -ex is not given but an ON ERROR-statement exists in the code, the program terminates instantaneously)
Very helpful is to use editors that are adapted to use this compiler
Convenient is the FBIDE (Integrated Development Environment for FreeBasic)
(make sure that you download FBIDE 0.4.6 only , not in a bundle including an older compiler version)
To introduce the compiler options click
View => Settings => FreeBasic
Compiler path e.g., [c:\Programme\FreeBASIC\fbc.exe]
Compiler command: "<$fbc>" "<$file>" -lang qb -ex

Also very powerful is the editor CONTEXT, available at
With the following setting, by pressing F9 the program will saved, compiled
and the compiler message will appear at the bottom of the screen; for this click:
Options => Environment options => Execute Keys => click F9
[Execute] [c:\Programme\FreeBasic\fbc] {or the actual path in use}
[Start in] %p
[Parameters] %f -lang qb -ex
[Windows] = >select Normal
[Hint] = > e.g., Compile FreeBasic
click on:  [capture console output]
click on:  [scroll to last line]

With the following setting, pressing F10 starts the current program
Options => Environment options => Execute Keys => click F10
[Execute]  %F
[Start in]  %p
[Windows] = >select Normal
[Hint] = >  Run
[Save] click on:  nothing

The turnaround is faster if you deactivate in
Options => General
the option [show user exec completion dialog]

Go to Editor View