1 /****************************************************************************

     2 **

     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

     4 ** All rights reserved.

     5 ** Contact: Nokia Corporation (qt-info@nokia.com)

     6 **

     7 ** This file is part of the QtGui module of the Qt Toolkit.

     8 **

     9 ** $QT_BEGIN_LICENSE:LGPL$

    10 ** No Commercial Usage

    11 ** This file contains pre-release code and may not be distributed.

    12 ** You may use this file in accordance with the terms and conditions

    13 ** contained in the Technology Preview License Agreement accompanying

    14 ** this package.

    15 **

    16 ** GNU Lesser General Public License Usage

    17 ** Alternatively, this file may be used under the terms of the GNU Lesser

    18 ** General Public License version 2.1 as published by the Free Software

    19 ** Foundation and appearing in the file LICENSE.LGPL included in the

    20 ** packaging of this file.  Please review the following information to

    21 ** ensure the GNU Lesser General Public License version 2.1 requirements

    22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

    23 **

    24 ** In addition, as a special exception, Nokia gives you certain additional

    25 ** rights.  These rights are described in the Nokia Qt LGPL Exception

    26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

    27 **

    28 ** If you have questions regarding the use of this file, please contact

    29 ** Nokia at qt-info@nokia.com.

    30 **

    31 **

    32 **

    33 **

    34 **

    35 **

    36 **

    37 **

    38 ** $QT_END_LICENSE$

    39 **

    40 ****************************************************************************/

    41 

    42 #ifndef QSIMPLEX_P_H

    43 #define QSIMPLEX_P_H

    44 

    45 //

    46 //  W A R N I N G

    47 //  -------------

    48 //

    49 // This file is not part of the Qt API.  It exists purely as an

    50 // implementation detail.  This header file may change from version to

    51 // version without notice, or even be removed.

    52 //

    53 // We mean it.

    54 //

    55 

    56 #include <QtCore/qhash.h>

    57 #include <QtCore/qpair.h>

    58 

    59 QT_BEGIN_NAMESPACE

    60 

    61 struct QSimplexVariable

    62 {

    63     QSimplexVariable() : result(0), index(0) {}

    64 

    65     qreal result;

    66     uint index;

    67 };

    68 

    69 

    70 /*!

    71   \internal

    72 

    73   Representation of a LP constraint like:

    74 

    75     (c1 * X1) + (c2 * X2) + ...  =  K

    76                              or <=  K

    77                              or >=  K

    78 

    79     Where (ci, Xi) are the pairs in "variables" and K the real "constant".

    80 */

    81 struct QSimplexConstraint

    82 {

    83     QSimplexConstraint() : constant(0), ratio(Equal), artificial(0) {}

    84 

    85     enum Ratio {

    86         LessOrEqual = 0,

    87         Equal,

    88         MoreOrEqual

    89     };

    90 

    91     QHash<QSimplexVariable *, qreal> variables;

    92     qreal constant;

    93     Ratio ratio;

    94 

    95     QPair<QSimplexVariable *, qreal> helper;

    96     QSimplexVariable * artificial;

    97 

    98 #ifdef QT_DEBUG

    99     bool isSatisfied() {

   100         qreal leftHandSide(0);

   101 

   102         QHash<QSimplexVariable *, qreal>::const_iterator iter;

   103         for (iter = variables.constBegin(); iter != variables.constEnd(); ++iter) {

   104             leftHandSide += iter.value() * iter.key()->result;

   105         }

   106 

   107         Q_ASSERT(constant > 0 || qFuzzyCompare(1, 1 + constant));

   108 

   109         if (qFuzzyCompare(1000 + leftHandSide, 1000 + constant))

   110             return true;

   111 

   112         switch (ratio) {

   113         case LessOrEqual:

   114             return leftHandSide < constant;

   115         case MoreOrEqual:

   116             return leftHandSide > constant;

   117         default:

   118             return false;

   119         }

   120     }

   121 #endif

   122 };

   123 

   124 class QSimplex

   125 {

   126 public:

   127     QSimplex();

   128     virtual ~QSimplex();

   129 

   130     qreal solveMin();

   131     qreal solveMax();

   132     QList<QSimplexVariable *> constraintsVariables();

   133 

   134     bool setConstraints(const QList<QSimplexConstraint *> constraints);

   135     void setObjective(QSimplexConstraint *objective);

   136 

   137     void dumpMatrix();

   138 

   139 private:

   140     // Matrix handling

   141     qreal valueAt(int row, int column);

   142     void setValueAt(int row, int column, qreal value);

   143     void clearRow(int rowIndex);

   144     void clearColumns(int first, int last);

   145     void combineRows(int toIndex, int fromIndex, qreal factor);

   146 

   147     // Simplex

   148     int findPivotColumn();

   149     int pivotRowForColumn(int column);

   150     void reducedRowEchelon();

   151     bool iterate();

   152 

   153     // Helpers

   154     void clearDataStructures();

   155     void solveMaxHelper();

   156     enum solverFactor { Minimum = -1, Maximum = 1 };

   157     qreal solver(solverFactor factor);

   158     void collectResults();

   159 

   160     QList<QSimplexConstraint *> constraints;

   161     QList<QSimplexVariable *> variables;

   162     QSimplexConstraint *objective;

   163 

   164     int rows;

   165     int columns;

   166     int firstArtificial;

   167 

   168     qreal *matrix;

   169 };

   170 

   171 inline QList<QSimplexVariable *> QSimplex::constraintsVariables()

   172 {

   173     return variables;

   174 }

   175 

   176 inline qreal QSimplex::valueAt(int rowIndex, int columnIndex)

   177 {

   178     return matrix[rowIndex * columns + columnIndex];

   179 }

   180 

   181 inline void QSimplex::setValueAt(int rowIndex, int columnIndex, qreal value)

   182 {

   183     matrix[rowIndex * columns + columnIndex] = value;

   184 }

   185 

   186 QT_END_NAMESPACE

   187 

   188 #endif // QSIMPLEX_P_H