/usr/include/qwt/qwt_spline.h is in libqwt-dev 6.0.0-1.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | /* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
* Qwt Widget Library
* Copyright (C) 1997 Josef Wilgen
* Copyright (C) 2002 Uwe Rathmann
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the Qwt License, Version 1.0
*****************************************************************************/
#ifndef QWT_SPLINE_H
#define QWT_SPLINE_H
#include "qwt_global.h"
#include <qpolygon.h>
#include <qvector.h>
/*!
\brief A class for spline interpolation
The QwtSpline class is used for cubical spline interpolation.
Two types of splines, natural and periodic, are supported.
\par Usage:
<ol>
<li>First call setPoints() to determine the spline coefficients
for a tabulated function y(x).
<li>After the coefficients have been set up, the interpolated
function value for an argument x can be determined by calling
QwtSpline::value().
</ol>
\par Example:
\code
#include <qwt_spline.h>
QPolygonF interpolate(const QPolygonF& points, int numValues)
{
QwtSpline spline;
if ( !spline.setPoints(points) )
return points;
QPolygonF interpolatedPoints(numValues);
const double delta =
(points[numPoints - 1].x() - points[0].x()) / (points.size() - 1);
for(i = 0; i < points.size(); i++) / interpolate
{
const double x = points[0].x() + i * delta;
interpolatedPoints[i].setX(x);
interpolatedPoints[i].setY(spline.value(x));
}
return interpolatedPoints;
}
\endcode
*/
class QWT_EXPORT QwtSpline
{
public:
//! Spline type
enum SplineType
{
//! A natural spline
Natural,
//! A periodic spline
Periodic
};
QwtSpline();
QwtSpline( const QwtSpline & );
~QwtSpline();
QwtSpline &operator=( const QwtSpline & );
void setSplineType( SplineType );
SplineType splineType() const;
bool setPoints( const QPolygonF& points );
QPolygonF points() const;
void reset();
bool isValid() const;
double value( double x ) const;
const QVector<double> &coefficientsA() const;
const QVector<double> &coefficientsB() const;
const QVector<double> &coefficientsC() const;
protected:
bool buildNaturalSpline( const QPolygonF & );
bool buildPeriodicSpline( const QPolygonF & );
private:
class PrivateData;
PrivateData *d_data;
};
#endif
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