Disposition is a library designed for generate permutations and combinations of elements, usual topics in combinatorial mathematics, and make easy for you to include them in your program.

The library is written in ANSI C and is released under the GPL license. You can download the last version of the program from the page of the project Disposition at SourceForge.

*Disposition* comes with a sample program, called
*disp*, to demonstrate an application of the library in the
generation of text strings:

$ disp `disp' prints permutations and combinations of characters. Usage: disp [-v|-r] TYPE CHARLIST [SIZE] TYPE must be one of these: -p|-pr|-c|-cr|-prr|-crr By default, the SIZE number is equal to the length of CHARLIST. -p Permutations (nPk) -pr Permutations with repetition (nPRk) -c Combinations (nCk) -cr Combinations with repetition (nCRk) -prr Permutations with "restricted" repetition -crr Combinations with "restricted" repetition CHARLIST string with the n characters used in the dispositions SIZE length k of every disposition, equal to n by default -v output in reverse order -r print only random dispositions For Permutations and Combinations with "restricted" repetition, characters in CHARLIST can be repeated to set the maximum number of times that each character can appear in the dispositions.

The following table shows different sequences generated with the
program *disp*:

$ disp -p abc abc acb bac bca cab cba |
$ disp -pr 01 4 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 |
$ disp -c aeiou 3 aei aeo aeu aio aiu aou eio eiu eou iou |
$ disp -v -cr ABC 4 CCCC BCCC BBCC BBBC BBBB ACCC ABCC ABBC ABBB AACC AABC AABB AAAC AAAB AAAA |

This is an example of program using the library to generate the
*permutations of 5 elements and size 3*, and print them:

#include "permutation.h" #include <stdio.h>intmain(void) { Permutation *perm;intnumelem, size, i; perm = newPermutation(numelem = 5, size = 3, NULL);if(!perm)return1; disp_first(perm);do{for(i = 0; i < disp_size(perm); i++) printf("%d ", disp_vec(perm)[i]); printf("\n"); }while(disp_next(perm)); disp_delete(perm);return0; }

You can find more information inside the package. For any
suggestions, bugs or ideas about this software, please mail me to:
**jasampler at yahoo dot es**