testBasis.cpp

// Copyright (C) 2003, International Business Machines
// Corporation and others.  All Rights Reserved.

#include "ClpSimplex.hpp"
#include "CoinHelperFunctions.hpp"
#include <iomanip>
#include <cassert>

int main (int argc, const char *argv[])
{
  ClpSimplex  model;
  int status;
  // Keep names
  if (argc<2) {
    status=model.readMps("small.mps",true);
  } else {
    status=model.readMps(argv[1],true);
  }
  if (status)
    exit(10);
  /*
    This driver turns a problem into all equalities, solves it and
    then creates optimal basis.
  */

  // copy of original
  ClpSimplex model2(model);
  // And another
  ClpSimplex model3(model);

  int originalNumberColumns = model.numberColumns();
  int numberRows = model.numberRows();

  int * addStarts = new int [numberRows+1];
  int * addRow = new int[numberRows];
  double * addElement = new double[numberRows];
  double * newUpper = new double[numberRows];
  double * newLower = new double[numberRows];

  double * lower = model2.rowLower();
  double * upper = model2.rowUpper();
  int iRow;
  // Simplest is to change all rhs to zero
  // One should skip E rows but this is simpler coding
  for (iRow=0;iRow<numberRows;iRow++) {
    newUpper[iRow]=upper[iRow];
    upper[iRow]=0.0;
    newLower[iRow]=lower[iRow];
    lower[iRow]=0.0;
    addRow[iRow]=iRow;
    addElement[iRow]=-1.0;
    addStarts[iRow]=iRow;
  }
  addStarts[numberRows]=numberRows;
  model2.addColumns(numberRows,newLower,newUpper,NULL,
                   addStarts,addRow,addElement);
  delete [] addStarts;
  delete [] addRow;
  delete [] addElement;
  delete [] newLower;
  delete [] newUpper;

  // Modify costs
  double * randomArray = new double[numberRows];
  for (iRow=0;iRow<numberRows;iRow++) 
    randomArray[iRow]=CoinDrand48();

  model2.transposeTimes(1.0,randomArray,model2.objective());
  delete [] randomArray;
  // solve
  model2.primal();
  // first check okay if solution values back
  memcpy(model.primalColumnSolution(),model2.primalColumnSolution(),
         originalNumberColumns*sizeof(double));
  memcpy(model.primalRowSolution(),model2.primalRowSolution(),
         numberRows*sizeof(double));
  int iColumn;
  for (iColumn=0;iColumn<originalNumberColumns;iColumn++) 
    model.setColumnStatus(iColumn,model2.getColumnStatus(iColumn));
  
  for (iRow=0;iRow<numberRows;iRow++) 
    model.setRowStatus(iRow,model2.getColumnStatus(iRow+originalNumberColumns));
  model.primal(0);
  // and now without solution values

  for (iColumn=0;iColumn<originalNumberColumns;iColumn++) 
    model3.setColumnStatus(iColumn,model2.getColumnStatus(iColumn));
  
  for (iRow=0;iRow<numberRows;iRow++) 
    model3.setRowStatus(iRow,model2.getColumnStatus(iRow+originalNumberColumns));
  model3.primal(0);
  return 0;
}    

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