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	Search   definiteintegralfunction.cpp /*************************************************************************** definiteintegralfunction.cpp - description ------------------- begin : Mon Nov 11 2002 copyright : (C) 2002 by Fungmeista email : mizunoami44@sourceforge.net ***************************************************************************/ /*************************************************************************** * * * This program is free software; you can redistribute it and/or modify * * it under the terms of the GNU General Public License as published by * * the Free Software Foundation; either version 2 of the License, or * * (at your option) any later version. * * * ***************************************************************************/ #include "definiteintegralfunction.h" #include <cmath> #include <qpainter.h> #include <qpointarray.h> #include <qobject.h> #include "fungparser.h" #include "fungmath.h" DefiniteIntegralFunction::DefiniteIntegralFunction(BasicGraph *graph, int expressions, double _precision) : MathFunction(graph,expressions), precision(_precision) { pointsStorage = new QPointArray; } DefiniteIntegralFunction::~DefiniteIntegralFunction() { delete pointsStorage; } void DefiniteIntegralFunction::calculate_and_draw(QPainter *painter) { if ( lowerBounds.x() > upperBounds.x() ) //bounds check { QString s( QObject::tr("Invalid bounds") ); setResult( s ); return; } pointsStorage->resize(upperBounds.x()-lowerBounds.x()+4); //add 1 so that both lower and upper bounds are included and another 2 so that the base of the figure is included double area = 0; (*pointsStorage)[upperBounds.x()-lowerBounds.x()+3] = QPoint(upperBounds.x(),toPixelYCoord(0)); for (int i=lowerBounds.x(); i<=upperBounds.x(); i++) { //use traprule to calculate definite integral double height = precision; //smaller height the more precise the answer double alpha[] = {toGraphXCoord(i),animatorValue()}; double alpha2[] = {toGraphXCoord(i+height),animatorValue()}; double baseone = expression->Eval(alpha); double basetwo = expression->Eval(alpha2); area += 0.5*(baseone+basetwo)*(toGraphXCoord(height)-toGraphXCoord(0)); (*pointsStorage)[i+1-lowerBounds.x()]=QPoint(i,toPixelYCoord(baseone)); (*pointsStorage)[i+2-lowerBounds.x()]=QPoint((int)(ROUND(i+height)),toPixelYCoord(basetwo)); } (*pointsStorage)[0] = QPoint(lowerBounds.x(),toPixelYCoord(0)); draw_stored(painter); QString s = QString("Definite Integral = %1").arg(area); setResult(s); } void DefiniteIntegralFunction::draw_stored(QPainter *painter) { painter->save(); painter->setBrush(QBrush(QColor(255,0,0),Qt::Dense4Pattern)); painter->drawPolygon(*pointsStorage); painter->restore(); }