The QwtSpline class is used for cubical spline interpolation. Two types of splines, natural and periodic, are supported.
#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 | 
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| Constructor. 
 Definition at line 73 of file qwt_spline.cpp. References d_data. | 
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| Destructor. 
 Definition at line 90 of file qwt_spline.cpp. References d_data. | 
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| Determines the coefficients for a natural spline. 
 
 Definition at line 209 of file qwt_spline.cpp. | 
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| Determines the coefficients for a periodic spline. 
 
 Definition at line 292 of file qwt_spline.cpp. | 
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| True if valid. 
 Definition at line 181 of file qwt_spline.cpp. References d_data. | 
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| Return points passed by setPoints Definition at line 164 of file qwt_spline.cpp. | 
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| Free allocated memory and set size to 0. 
 Definition at line 172 of file qwt_spline.cpp. References d_data. | 
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| 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. 
 
 
 
 Definition at line 126 of file qwt_spline.cpp. | 
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| Calculate the interpolated function value corresponding to a given argument x. Definition at line 190 of file qwt_spline.cpp. References d_data. | 
 1.4.6
 1.4.6