00001 #include "MusimatChapter9.h" 00002 MusimatChapter9Section(C091201c) { 00003 Print("*** Permutation ***"); 00004 /***************************************************************************** 00005 00006 Permutation 00007 00008 Iterate the supplied sequence in prime order until exhausted, then permute the 00009 entire row by inc steps and repeat from the beginning. 00010 *****************************************************************************/ 00011 para1(); // Step into this function to continue. 00012 } 00013 00014 Integer permute(IntegerList L, Integer Reference pos, 00015 Integer Reference count, Integer inc) { 00016 Integer curPos = pos; // save current position 00017 Integer x = cycle(L, pos, 1); // update pos and get list value 00018 count = count + 1; // increment counter 00019 If (count == Length(L)) { // have we output L items from list? 00020 count = 0; // reset count 00021 pos = curPos + inc; // permute position for next time 00022 } 00023 Return(x); 00024 } 00025 00026 Static Void para1() { 00027 /***************************************************************************** 00028 Here is an example of invoking permute(). 00029 *****************************************************************************/ 00030 Print("*** Permutation ***"); 00031 IntegerList L(10, 11, 12); 00032 Integer inc = -1; 00033 Integer pos = 0; 00034 Integer perm = 0; 00035 00036 For (Integer i = 0; i < 3 * Length(L); i++) { 00037 Print(permute(L, pos, perm, inc)); 00038 } 00039 00040 /***************************************************************************** 00041 prints 10, 11, 12, 11, 12, 10, 12, 10, 11. Because inc = -1, it skips back one place in the 00042 row every time. The trigger for it to skip is when it has output as many elements as are in the list. 00043 *****************************************************************************/ 00044 } 00045 00047 /* $Revision: 1.3 $ $Date: 2006/09/05 08:02:45 $ $Author: dgl $ $Name: $ $Id: C091201c.cpp,v 1.3 2006/09/05 08:02:45 dgl Exp $ */ 00048 // The Musimat Tutorial © 2006 Gareth Loy 00049 // Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" © 2006 Gareth Loy 00050 // and published exclusively by The MIT Press. 00051 // This program is released WITHOUT ANY WARRANTY; without even the implied 00052 // warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 00053 // For information on usage and redistribution, and for a DISCLAIMER OF ALL 00054 // WARRANTIES, see the file, "LICENSE.txt," in this distribution. 00055 // "Musimathics" is available here: http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916 00056 // Gareth Loy's Musimathics website: http://www.musimathics.com/ 00057 // The Musimat website: http://www.musimat.com/ 00058 // This program is released under the terms of the GNU General Public License 00059 // available here: http://www.gnu.org/licenses/gpl.txt 00060
1.7.2