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/* $Id: dualCuts.cpp 1662 2011-01-04 17:52:40Z lou $ */
/*
Copyright (C) 2003, International Business Machines Corporation and others.
All Rights Reserved.
This sample program is designed to illustrate programming techniques
using CoinLP, has not been thoroughly tested and comes without any
warranty whatsoever.
You may copy, modify and distribute this sample program without any
restrictions whatsoever and without any payment to anyone.
*/
#include "ClpSimplex.hpp"
#include "ClpPresolve.hpp"
#include "ClpFactorization.hpp"
#include "CoinSort.hpp"
#include "CoinHelperFunctions.hpp"
#include "CoinTime.hpp"
#include "CoinMpsIO.hpp"
#include <iomanip>
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], false);
}
if (status)
exit(10);
/*
This driver implements a method of treating a problem as all cuts.
So it adds in all E rows, solves and then adds in violated rows.
*/
double time1 = CoinCpuTime();
ClpSimplex * model2;
ClpPresolve pinfo;
int numberPasses = 5; // can change this
/* Use a tolerance of 1.0e-8 for feasibility, treat problem as
not being integer, do "numberpasses" passes and throw away names
in presolved model */
model2 = pinfo.presolvedModel(model, 1.0e-8, false, numberPasses, false);
if (!model2) {
fprintf(stderr, "ClpPresolve says %s is infeasible with tolerance of %g\n",
argv[1], 1.0e-8);
fprintf(stdout, "ClpPresolve says %s is infeasible with tolerance of %g\n",
argv[1], 1.0e-8);
// model was infeasible - maybe try again with looser tolerances
model2 = pinfo.presolvedModel(model, 1.0e-7, false, numberPasses, false);
if (!model2) {
fprintf(stderr, "ClpPresolve says %s is infeasible with tolerance of %g\n",
argv[1], 1.0e-7);
fprintf(stdout, "ClpPresolve says %s is infeasible with tolerance of %g\n",
argv[1], 1.0e-7);
exit(2);
}
}
// change factorization frequency from 200
model2->setFactorizationFrequency(100 + model2->numberRows() / 50);
int numberColumns = model2->numberColumns();
int originalNumberRows = model2->numberRows();
// We will need arrays to choose rows to add
double * weight = new double [originalNumberRows];
int * sort = new int [originalNumberRows];
int numberSort = 0;
char * take = new char [originalNumberRows];
const double * rowLower = model2->rowLower();
const double * rowUpper = model2->rowUpper();
int iRow, iColumn;
// Set up initial list
numberSort = 0;
for (iRow = 0; iRow < originalNumberRows; iRow++) {
weight[iRow] = 1.123e50;
if (rowLower[iRow] == rowUpper[iRow]) {
sort[numberSort++] = iRow;
weight[iRow] = 0.0;
}
}
numberSort /= 2;
// Just add this number of rows each time in small problem
int smallNumberRows = 2 * numberColumns;
smallNumberRows = CoinMin(smallNumberRows, originalNumberRows / 20);
// and pad out with random rows
double ratio = ((double)(smallNumberRows - numberSort)) / ((double) originalNumberRows);
for (iRow = 0; iRow < originalNumberRows; iRow++) {
if (weight[iRow] == 1.123e50 && CoinDrand48() < ratio)
sort[numberSort++] = iRow;
}
/* This is optional.
The best thing to do is to miss out random rows and do a set which makes dual feasible.
If that is not possible then make sure variables have bounds.
One way that normally works is to automatically tighten bounds.
*/
#if 0
// However for some we need to do anyway
double * columnLower = model2->columnLower();
double * columnUpper = model2->columnUpper();
for (iColumn = 0; iColumn < numberColumns; iColumn++) {
columnLower[iColumn] = CoinMax(-1.0e6, columnLower[iColumn]);
columnUpper[iColumn] = CoinMin(1.0e6, columnUpper[iColumn]);
}
#endif
model2->tightenPrimalBounds(-1.0e4, true);
printf("%d rows in initial problem\n", numberSort);
double * fullSolution = model2->primalRowSolution();
// Just do this number of passes
int maxPass = 50;
// And take out slack rows until this pass
int takeOutPass = 30;
int iPass;
const int * start = model2->clpMatrix()->getVectorStarts();
const int * length = model2->clpMatrix()->getVectorLengths();
const int * row = model2->clpMatrix()->getIndices();
int * whichColumns = new int [numberColumns];
for (iColumn = 0; iColumn < numberColumns; iColumn++)
whichColumns[iColumn] = iColumn;
int numberSmallColumns = numberColumns;
for (iPass = 0; iPass < maxPass; iPass++) {
printf("Start of pass %d\n", iPass);
// Cleaner this way
std::sort(sort, sort + numberSort);
// Create small problem
ClpSimplex small(model2, numberSort, sort, numberSmallColumns, whichColumns);
small.setFactorizationFrequency(100 + numberSort / 200);
//small.setPerturbation(50);
//small.setLogLevel(63);
// A variation is to just do N iterations
//if (iPass)
//small.setMaximumIterations(100);
// Solve
small.factorization()->messageLevel(8);
if (iPass) {
small.dual();
} else {
small.writeMps("continf.mps");
ClpSolve solveOptions;
solveOptions.setSolveType(ClpSolve::useDual);
//solveOptions.setSolveType(ClpSolve::usePrimalorSprint);
//solveOptions.setSpecialOption(1,2,200); // idiot
small.initialSolve(solveOptions);
}
bool dualInfeasible = (small.status() == 2);
// move solution back
double * solution = model2->primalColumnSolution();
const double * smallSolution = small.primalColumnSolution();
for (int j = 0; j < numberSmallColumns; j++) {
iColumn = whichColumns[j];
solution[iColumn] = smallSolution[j];
model2->setColumnStatus(iColumn, small.getColumnStatus(j));
}
for (iRow = 0; iRow < numberSort; iRow++) {
int kRow = sort[iRow];
model2->setRowStatus(kRow, small.getRowStatus(iRow));
}
// compute full solution
memset(fullSolution, 0, originalNumberRows * sizeof(double));
model2->times(1.0, model2->primalColumnSolution(), fullSolution);
if (iPass != maxPass - 1) {
// Mark row as not looked at
for (iRow = 0; iRow < originalNumberRows; iRow++)
weight[iRow] = 1.123e50;
// Look at rows already in small problem
int iSort;
int numberDropped = 0;
int numberKept = 0;
int numberBinding = 0;
int numberInfeasibilities = 0;
double sumInfeasibilities = 0.0;
for (iSort = 0; iSort < numberSort; iSort++) {
iRow = sort[iSort];
//printf("%d %g %g\n",iRow,fullSolution[iRow],small.primalRowSolution()[iSort]);
if (model2->getRowStatus(iRow) == ClpSimplex::basic) {
// Basic - we can get rid of if early on
if (iPass < takeOutPass && !dualInfeasible) {
// may have hit max iterations so check
double infeasibility = CoinMax(fullSolution[iRow] - rowUpper[iRow],
rowLower[iRow] - fullSolution[iRow]);
weight[iRow] = -infeasibility;
if (infeasibility > 1.0e-8) {
numberInfeasibilities++;
sumInfeasibilities += infeasibility;
} else {
weight[iRow] = 1.0;
numberDropped++;
}
} else {
// keep
weight[iRow] = -1.0e40;
numberKept++;
}
} else {
// keep
weight[iRow] = -1.0e50;
numberKept++;
numberBinding++;
}
}
// Now rest
for (iRow = 0; iRow < originalNumberRows; iRow++) {
sort[iRow] = iRow;
if (weight[iRow] == 1.123e50) {
// not looked at yet
double infeasibility = CoinMax(fullSolution[iRow] - rowUpper[iRow],
rowLower[iRow] - fullSolution[iRow]);
weight[iRow] = -infeasibility;
if (infeasibility > 1.0e-8) {
numberInfeasibilities++;
sumInfeasibilities += infeasibility;
}
}
}
// sort
CoinSort_2(weight, weight + originalNumberRows, sort);
numberSort = CoinMin(originalNumberRows, smallNumberRows + numberKept);
memset(take, 0, originalNumberRows);
for (iRow = 0; iRow < numberSort; iRow++)
take[sort[iRow]] = 1;
numberSmallColumns = 0;
for (iColumn = 0; iColumn < numberColumns; iColumn++) {
int n = 0;
for (int j = start[iColumn]; j < start[iColumn] + length[iColumn]; j++) {
int iRow = row[j];
if (take[iRow])
n++;
}
if (n)
whichColumns[numberSmallColumns++] = iColumn;
}
printf("%d rows binding, %d rows kept, %d rows dropped - new size %d rows, %d columns\n",
numberBinding, numberKept, numberDropped, numberSort, numberSmallColumns);
printf("%d rows are infeasible - sum is %g\n", numberInfeasibilities,
sumInfeasibilities);
if (!numberInfeasibilities) {
printf("Exiting as looks optimal\n");
break;
}
numberInfeasibilities = 0;
sumInfeasibilities = 0.0;
for (iSort = 0; iSort < numberSort; iSort++) {
if (weight[iSort] > -1.0e30 && weight[iSort] < -1.0e-8) {
numberInfeasibilities++;
sumInfeasibilities += -weight[iSort];
}
}
printf("in small model %d rows are infeasible - sum is %g\n", numberInfeasibilities,
sumInfeasibilities);
}
}
delete [] weight;
delete [] sort;
delete [] whichColumns;
delete [] take;
// If problem is big you may wish to skip this
model2->dual();
int numberBinding = 0;
for (iRow = 0; iRow < originalNumberRows; iRow++) {
if (model2->getRowStatus(iRow) != ClpSimplex::basic)
numberBinding++;
}
printf("%d binding rows at end\n", numberBinding);
pinfo.postsolve(true);
int numberIterations = model2->numberIterations();;
delete model2;
/* After this postsolve model should be optimal.
We can use checkSolution and test feasibility */
model.checkSolution();
if (model.numberDualInfeasibilities() ||
model.numberPrimalInfeasibilities())
printf("%g dual %g(%d) Primal %g(%d)\n",
model.objectiveValue(),
model.sumDualInfeasibilities(),
model.numberDualInfeasibilities(),
model.sumPrimalInfeasibilities(),
model.numberPrimalInfeasibilities());
// But resolve for safety
model.primal(1);
numberIterations += model.numberIterations();;
printf("Solve took %g seconds\n", CoinCpuTime() - time1);
return 0;
}
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