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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QSIMPLEX_P_H
#define QSIMPLEX_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <QtCore/qhash.h>
#include <QtCore/qpair.h>
QT_BEGIN_NAMESPACE
struct QSimplexVariable
{
QSimplexVariable() : result(0), index(0) {}
qreal result;
int index;
};
/*!
\internal
Representation of a LP constraint like:
(c1 * X1) + (c2 * X2) + ... = K
or <= K
or >= K
Where (ci, Xi) are the pairs in "variables" and K the real "constant".
*/
struct QSimplexConstraint
{
QSimplexConstraint() : constant(0), ratio(Equal), artificial(0) {}
enum Ratio {
LessOrEqual = 0,
Equal,
MoreOrEqual
};
QHash<QSimplexVariable *, qreal> variables;
qreal constant;
Ratio ratio;
QPair<QSimplexVariable *, qreal> helper;
QSimplexVariable * artificial;
void invert();
bool isSatisfied() {
qreal leftHandSide(0);
QHash<QSimplexVariable *, qreal>::const_iterator iter;
for (iter = variables.constBegin(); iter != variables.constEnd(); ++iter) {
leftHandSide += iter.value() * iter.key()->result;
}
Q_ASSERT(constant > 0 || qFuzzyCompare(1, 1 + constant));
if ((leftHandSide == constant) || qAbs(leftHandSide - constant) < 0.0000001)
return true;
switch (ratio) {
case LessOrEqual:
return leftHandSide < constant;
case MoreOrEqual:
return leftHandSide > constant;
default:
return false;
}
}
#ifdef QT_DEBUG
QString toString() {
QString result;
result += QString::fromAscii("-- QSimplexConstraint %1 --").arg(quintptr(this), 0, 16);
QHash<QSimplexVariable *, qreal>::const_iterator iter;
for (iter = variables.constBegin(); iter != variables.constEnd(); ++iter) {
result += QString::fromAscii(" %1 x %2").arg(iter.value()).arg(quintptr(iter.key()), 0, 16);
}
switch (ratio) {
case LessOrEqual:
result += QString::fromAscii(" (less) <= %1").arg(constant);
break;
case MoreOrEqual:
result += QString::fromAscii(" (more) >= %1").arg(constant);
break;
default:
result += QString::fromAscii(" (eqal) == %1").arg(constant);
}
return result;
}
#endif
};
class QSimplex
{
public:
QSimplex();
virtual ~QSimplex();
qreal solveMin();
qreal solveMax();
bool setConstraints(const QList<QSimplexConstraint *> constraints);
void setObjective(QSimplexConstraint *objective);
void dumpMatrix();
private:
// Matrix handling
qreal valueAt(int row, int column);
void setValueAt(int row, int column, qreal value);
void clearRow(int rowIndex);
void clearColumns(int first, int last);
void combineRows(int toIndex, int fromIndex, qreal factor);
// Simplex
bool simplifyConstraints(QList<QSimplexConstraint *> *constraints);
int findPivotColumn();
int pivotRowForColumn(int column);
void reducedRowEchelon();
bool iterate();
// Helpers
void clearDataStructures();
void solveMaxHelper();
enum solverFactor { Minimum = -1, Maximum = 1 };
qreal solver(solverFactor factor);
void collectResults();
QList<QSimplexConstraint *> constraints;
QList<QSimplexVariable *> variables;
QSimplexConstraint *objective;
int rows;
int columns;
int firstArtificial;
qreal *matrix;
};
inline qreal QSimplex::valueAt(int rowIndex, int columnIndex)
{
return matrix[rowIndex * columns + columnIndex];
}
inline void QSimplex::setValueAt(int rowIndex, int columnIndex, qreal value)
{
matrix[rowIndex * columns + columnIndex] = value;
}
QT_END_NAMESPACE
#endif // QSIMPLEX_P_H
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