102 lines
2.4 KiB
C
102 lines
2.4 KiB
C
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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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* Qwt Widget Library
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* Copyright (C) 1997 Josef Wilgen
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* Copyright (C) 2002 Uwe Rathmann
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the Qwt License, Version 1.0
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*****************************************************************************/
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#ifndef QWT_SPLINE_H
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#define QWT_SPLINE_H
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#include "qwt_global.h"
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#include <qpolygon.h>
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#include <qvector.h>
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/*!
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\brief A class for spline interpolation
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The QwtSpline class is used for cubical spline interpolation.
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Two types of splines, natural and periodic, are supported.
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\par Usage:
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<ol>
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<li>First call setPoints() to determine the spline coefficients
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for a tabulated function y(x).
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<li>After the coefficients have been set up, the interpolated
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function value for an argument x can be determined by calling
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QwtSpline::value().
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</ol>
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\par Example:
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\code
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#include <qwt_spline.h>
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QPolygonF interpolate(const QPolygonF& points, int numValues)
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{
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QwtSpline spline;
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if ( !spline.setPoints(points) )
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return points;
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QPolygonF interpolatedPoints(numValues);
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const double delta =
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(points[numPoints - 1].x() - points[0].x()) / (points.size() - 1);
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for(i = 0; i < points.size(); i++) / interpolate
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{
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const double x = points[0].x() + i * delta;
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interpolatedPoints[i].setX(x);
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interpolatedPoints[i].setY(spline.value(x));
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}
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return interpolatedPoints;
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}
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\endcode
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*/
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class QWT_EXPORT QwtSpline
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{
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public:
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//! Spline type
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enum SplineType
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{
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//! A natural spline
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Natural,
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//! A periodic spline
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Periodic
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};
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QwtSpline();
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QwtSpline( const QwtSpline & );
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~QwtSpline();
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QwtSpline &operator=( const QwtSpline & );
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void setSplineType( SplineType );
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SplineType splineType() const;
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bool setPoints( const QPolygonF& points );
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QPolygonF points() const;
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void reset();
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bool isValid() const;
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double value( double x ) const;
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const QVector<double> &coefficientsA() const;
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const QVector<double> &coefficientsB() const;
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const QVector<double> &coefficientsC() const;
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protected:
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bool buildNaturalSpline( const QPolygonF & );
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bool buildPeriodicSpline( const QPolygonF & );
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private:
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class PrivateData;
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PrivateData *d_data;
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};
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#endif
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