/*********************************************************************** Xpress Optimizer Examples ========================= file Polygon_textformula.c `````````````````````````` Implement the polygon example using text formulas Maximize the area of polygon of N vertices and diameter of 1 The position of vertices is indicated as (rho,theta) coordinates where rho denotes the distance to the base point (vertex with number N) and theta the angle from the x-axis. The nonlinear expressions are described text based input. (c) 2017 Fair Isaac Corporation ***********************************************************************/ #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "xprs.h"
#include "xslp.h"

#define MAXROW 20
#define MAXCOL 20
#define MAXELT 50

void XPRS_CC XSLPMessage(XSLPprob my_prob, void *my_object, char *msg,
  int len, int msg_type);

int main(int argc, char *argv[]) {
  XPRSprob xprob = NULL;
  XSLPprob sprob = NULL;

  int nRow, nCol, nSide, nElement, nRowName, nColName;
  int iRow;
  char RowType[MAXROW];
  double RHS[MAXROW], OBJ[MAXCOL], Element[MAXELT], Lower[MAXCOL], Upper[MAXCOL];
  int ColStart[MAXCOL+1], RowIndex[MAXELT];
  double Factor;
  int ReturnValue;
  int i, j;
  char RowNames[500], ColNames[500];
  char *CoefBuffer;
  int BufferPos;

/* Initialisation */
  CoefBuffer = NULL;
  if (ReturnValue=XPRSinit(NULL)) goto ErrorReturn;
  if (ReturnValue=XSLPinit()) goto ErrorReturn;
  if (ReturnValue=XPRScreateprob(&xprob)) goto ErrorReturn;
  if (ReturnValue=XSLPcreateprob(&sprob,&xprob)) goto ErrorReturn;

/* XSLPsetcbmessage */
  XSLPsetcbmessage(sprob,XSLPMessage,NULL);

  nSide = 5;
  nRowName = 0;

/* Rows */
  nRow = nSide-2 + (nSide-1)*(nSide-2)/2 + 1;
  for (i=0;i<nRow;i++) RHS[i]=0; nRow=0; RowType[nRow++]='E' OBJEQ nRowName=nRowName for (i=1;i<nSide-1;i++) T2T1 T4T3 (j=i+1;j<nSide;j++) RowType[nRow]='L' RHS[nRow++]=1.0; Columns nColName=0; nCol=(nSide-1)*2 nElement=0; OBJ[i]=0; objective function Lower[i]=0; lower bound normally zero Upper[i]=XPRS_PLUSINFINITY; upper infinity OBJX ColStart[nCol]=nElement; OBJ[nCol]=1.0; Lower[nCol++]=XPRS_MINUSINFINITY; free column Element[nElement]=-1.0; RowIndex[nElement++]=0; THETA1 THETA iRow=0; ColStart[nCol++]=nElement; if> 1) {
	    Element[nElement] = 1;
	    RowIndex[nElement++] = iRow;
	  }
	  iRow++;
  }

  Upper[nCol-1] = 3,142;

/* Equals column */
  nColName = nColName + 1 + sprintf(&ColNames[nColName],"=");
  ColStart[nCol] = nElement;
  Lower[nCol] = Upper[nCol] = 1; /* fixed at 1 */
  nCol++;

/* Remaining columns come later */
  for (i=1;i<nSide;i++) Lower[nCol]=0.01; lower bound Upper[nCol]=1; ColStart[nCol++]=nElement; nColName=nColName ColStart[nCol]=nElement; if (ReturnValue=XPRSloadlp(xprob,"Polygon",nCol,nRow,RowType,RHS,NULL,OBJ, goto Build up nonlinear coefficients Allow space for largest formula approx characters per side area CoefBuffer=(char Area Factor=0.5; BufferPos=0; (i=1;i<nSide-1;i++)> 1) {
	    BufferPos = BufferPos + sprintf(&CoefBuffer[BufferPos]," + ");
	  }
	  BufferPos = BufferPos + sprintf(&CoefBuffer[BufferPos],
                                      "RHO%d * RHO%d * SIN ( THETA%d - THETA%d )",i+1,i,i+1,i);
  }
  XSLPchgccoef(sprob,0,nSide,&Factor,CoefBuffer);

/* Distances */
  Factor = 1;
  for (i=1;i<nSide-1;i++) {
	  for (j=i+1;j<nSide;j++) {
	    sprintf(CoefBuffer,"RHO%d ^ 2 + RHO%d ^ 2 - 2 * RHO%d * RHO%d * COS ( THETA%d - THETA%d )",
                j,i,j,i,j,i);
	    XSLPchgccoef(sprob,iRow,nSide,&Factor,CoefBuffer);
	    iRow++;
	  }
  }

  XSLPwriteprob(sprob,"Polygon_textformula","");

  if (ReturnValue=XSLPmaxim(sprob,"")) goto ErrorReturn;
  if (ReturnValue=XSLPwriteslxsol(sprob, "Polygon_textformula", "")) goto ErrorReturn; 

  goto NormalReturn;
ErrorReturn:
  printf("\nError %d",ReturnValue);
NormalReturn:
  if (CoefBuffer) free(CoefBuffer);
  XSLPdestroyprob(sprob);
  XPRSdestroyprob(xprob);
  XSLPfree();
  XPRSfree();
  return(ReturnValue);
}

void XPRS_CC XSLPMessage(XSLPprob my_prob, void *my_object, char *msg,
  int len, int msg_type) {
  switch (msg_type) {
  case 4: /* error */
  case 3: /* warning */
  case 2: /* dialogue */
  case 1: /* information */
	printf("%s\n",msg);
	break;
  default: /* exiting */
	fflush(stdout);
	break;
  }
}