/********************************************************
BCL Example Problems
====================
file xbpurch.c
``````````````
Purchasing problem.
Using SOS-2.
(c) 2008 Fair Isaac Corporation
author: S.Heipcke, Jan. 2000, rev. Mar. 2011
********************************************************/
/* WARNING. This model is not for the novice, but it does contain many *
* useful ideas. *
* The formulation is tricky because the discounts are all-quantity, so *
* the graph of cost against quantity purchased is discontinuous. *
* To maintain sanity in the special ordered set formulation, we must *
* coarsen the discontinuity by stopping purchases just at the break point. */
#include
#include
#include "xprb.h"
#define PARAMSFILE XPRBDATAPATH "/purchase/params.dat"
#define MAXPERCFILE XPRBDATAPATH "/purchase/maxperc.dat"
#define REQFILE XPRBDATAPATH "/purchase/required.dat"
#define PRICEFILE XPRBDATAPATH "/purchase/pricebk.dat"
/****TABLES****/
int NS; /* Number of suppliers */
int NB; /* Number of price breaks */
int NB2; /* Useful parameter */
double **UC; /* Unit cost */
double **BR; /* Breakpoints (quantities at which unit cost changes) */
double **X; /* Coarsened break points */
double **C; /* Total cost at break points */
double *DELTA; /* Coarsening factors */
double *MAXPERC; /* Maximum percentage from each supplier */
double REQ; /* Total quantity required */
double delta = 0.10; /* Base coarsening factor */
/***********************************************************************/
void modpurchase(XPRBprob prob)
{
XPRBctr *refrow, cobj,ctr;
int s,b;
XPRBvar *x,**lam;
XPRBsos sos2;
/****VARIABLES****/
x=(XPRBvar *)malloc(NS*sizeof(XPRBvar));
for(s=0;s |
