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QwtSpline
Langue: en
Version: 160824 (fedora - 05/07/09)
Section: 3 (Bibliothèques de fonctions)
Sommaire
- NAME
- SYNOPSIS
- Detailed Description
- Constructor & Destructor Documentation
- Member Function Documentation
- bool QwtSpline::setPoints (const QPolygonF & points)
- QPolygonF QwtSpline::points () const
- void QwtSpline::reset ()
- bool QwtSpline::isValid () const
- double QwtSpline::value (double x) const
- bool QwtSpline::buildNaturalSpline (const QPolygonF & points) [protected]
- bool QwtSpline::buildPeriodicSpline (const QPolygonF & points) [protected]
- Author
NAME
QwtSpline -SYNOPSIS
Detailed Description
A class for spline interpolation.
The QwtSpline class is used for cubical spline interpolation. Two types of splines, natural and periodic, are supported.
Usage:.RS 4
- 1.
- First call setPoints() to determine the spline coefficients for a tabulated function y(x).
- 2.
- After the coefficients have been set up, the interpolated function value for an argument x can be determined by calling QwtSpline::value().
Example:.RS 4
#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; }
Definition at line 77 of file qwt_spline.h.
Public Types
enum SplineType { Natural, Periodic }
Public Member Functions
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
Protected Member Functions
bool buildNaturalSpline (const QPolygonF &)
bool buildPeriodicSpline (const QPolygonF &)
Protected Attributes
PrivateData * d_data
Constructor & Destructor Documentation
QwtSpline::QwtSpline ()
Constructor.
Definition at line 73 of file qwt_spline.cpp.
References d_data.
QwtSpline::~QwtSpline ()
Destructor.
Definition at line 90 of file qwt_spline.cpp.
References d_data.
Member Function Documentation
bool QwtSpline::setPoints (const QPolygonF & points)
Determine the function table index corresponding to a value x Calculate the spline coefficients.
Depending on the value of periodic, this function will determine the coefficients for a natural or a periodic spline and store them internally.
Parameters:
- x
y points
size number of points
periodic if true, calculate periodic spline
Returns:
- true if successful
Warning:
- The sequence of x (but not y) values has to be strictly monotone increasing, which means x[0] < x[1] < .... < x[n-1]. If this is not the case, the function will return false
Definition at line 126 of file qwt_spline.cpp.
QPolygonF QwtSpline::points () const
Return points passed by setPoints
Definition at line 164 of file qwt_spline.cpp.
void QwtSpline::reset ()
Free allocated memory and set size to 0.
Definition at line 172 of file qwt_spline.cpp.
References d_data.
bool QwtSpline::isValid () const
True if valid.
Definition at line 181 of file qwt_spline.cpp.
References d_data.
double QwtSpline::value (double x) const
Calculate the interpolated function value corresponding to a given argument x.
Definition at line 190 of file qwt_spline.cpp.
References d_data.
bool QwtSpline::buildNaturalSpline (const QPolygonF & points) [protected]
Determines the coefficients for a natural spline.
Returns:
- true if successful
Definition at line 209 of file qwt_spline.cpp.
bool QwtSpline::buildPeriodicSpline (const QPolygonF & points) [protected]
Determines the coefficients for a periodic spline.
Returns:
- true if successful
Definition at line 292 of file qwt_spline.cpp.
Author
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