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104 lines
2.6 KiB
104 lines
2.6 KiB
/**************************************************************************
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randomlist.cpp - Some "random functions" :-)
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Copyright (C) 1997,98 Antonio Larrosa Jimenez
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307, USA.
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Send comments and bug fixes to larrosa@kde.org
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or to Antonio Larrosa, Rio Arnoya, 10 5B, 29006 Malaga, Spain
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***************************************************************************/
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#include "randomlist.h"
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#include <stdlib.h>
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#include <stdio.h>
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#define RAND_UNIFORM (double)rand()/(double)RAND_MAX
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int random_discrete(double *distrib,int n)
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{
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int i=0;
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double g=0.0;
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double z=0.0;
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while ((z==0.0)||(z==1.0)) z=RAND_UNIFORM;
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while ((g<z)&&(i<n))
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{
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g+=distrib[i];
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i++;
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};
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return i-1;
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}
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double *generate_discrete_uniform_distrib(int n)
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{
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double *distrib=new double[n];
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for (int i=0;i<n;i++)
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distrib[i]=1.0/(double)n;
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return distrib;
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}
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void remove_lmn_from_discrete_distrib(int k,double *distrib,int n,int used=0)
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{
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int i;
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if (used==0) //guess how many values of the v.a. are strictly positive
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{
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for (i=0;i<n;i++) if (distrib[i]>0) used++;
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};
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used--; // k will no longer be used :-)
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if (used==0) return;
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double piece=distrib[k]/(double)used;
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distrib[k]=0.0;
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for (i=0;i<n;i++) if (distrib[i]>0) distrib[i]+=piece;
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}
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void show_distrib(double *distrib,int n)
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{
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printf("(");
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for (int j=0;j<n;j++) printf("%g,",distrib[j]);
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printf(")\n");
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}
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int *generate_random_list(int n)
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{
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if (n==0) return NULL;
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int *list=new int[n];
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double *distrib=generate_discrete_uniform_distrib(n);
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int used=n;
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int x;
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int i=1;
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while (used>0)
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{
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x=random_discrete(distrib,n);
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list[x]=i;
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i++;
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remove_lmn_from_discrete_distrib(x,distrib,n,used);
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used--;
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};
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delete distrib;
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return list;
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}
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int *generate_list(int n)
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{
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int *list=new int[n];
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for (int i=0;i<n;i++)
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list[i]=i+1;
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return list;
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}
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