granicus.if.org Git - postgresql/blob - src/backend/optimizer/geqo/geqo_mutation.c

   1 /*------------------------------------------------------------------------
   2 *
   3 * geqo_mutation.c
   4 *
   5 *        TSP mutation routines
   6 *
   7 * src/backend/optimizer/geqo/geqo_mutation.c
   8 *
   9 *-------------------------------------------------------------------------
  10 */
  11
  12 /* contributed by:
  13    =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  14    *  Martin Utesch                              * Institute of Automatic Control          *
  15    =                                                     = University of Mining and Technology =
  16    *  utesch@aut.tu-freiberg.de  * Freiberg, Germany                               *
  17    =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  18  */
  19
  20 /* this is adopted from Genitor : */
  21 /*************************************************************/
  22 /*                                                                                                                       */
  23 /*      Copyright (c) 1990                                                                               */
  24 /*      Darrell L. Whitley                                                                               */
  25 /*      Computer Science Department                                                              */
  26 /*      Colorado State University                                                                */
  27 /*                                                                                                                       */
  28 /*      Permission is hereby granted to copy all or any part of  */
  29 /*      this program for free distribution.   The author's name  */
  30 /*      and this copyright notice must be included in any copy.  */
  31 /*                                                                                                                       */
  32 /*************************************************************/
  33
  34 #include "postgres.h"
  35 #include "optimizer/geqo_mutation.h"
  36 #include "optimizer/geqo_random.h"
  37
  38 #if defined(CX)                                 /* currently used only in CX mode */
  39
  40 void
  41 geqo_mutation(PlannerInfo *root, Gene *tour, int num_gene)
  42 {
  43         int                     swap1;
  44         int                     swap2;
  45         int                     num_swaps = geqo_randint(root, num_gene / 3, 0);
  46         Gene            temp;
  47
  48
  49         while (num_swaps > 0)
  50         {
  51                 swap1 = geqo_randint(root, num_gene - 1, 0);
  52                 swap2 = geqo_randint(root, num_gene - 1, 0);
  53
  54                 while (swap1 == swap2)
  55                         swap2 = geqo_randint(root, num_gene - 1, 0);
  56
  57                 temp = tour[swap1];
  58                 tour[swap1] = tour[swap2];
  59                 tour[swap2] = temp;
  60
  61
  62                 num_swaps -= 1;
  63         }
  64 }
  65
  66 #endif                                                  /* defined(CX) */