.TH "QwtSpline" 3 "Mon Aug 1 2011" "Version 5.2.2" "Qwt User's Guide" \" -*- nroff -*-
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.SH NAME
QwtSpline \- 
.PP
A class for spline interpolation.  

.SH SYNOPSIS
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.PP
.PP
\fC#include <qwt_spline.h>\fP
.SS "Public Types"

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.RI "enum \fBSplineType\fP { \fBNatural\fP, \fBPeriodic\fP }"
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.SS "Public Member Functions"

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.RI "const QwtArray< double > & \fBcoefficientsA\fP () const "
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.RI "const QwtArray< double > & \fBcoefficientsB\fP () const "
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.RI "const QwtArray< double > & \fBcoefficientsC\fP () const "
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.RI "bool \fBisValid\fP () const "
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.RI "\fBQwtSpline\fP & \fBoperator=\fP (const \fBQwtSpline\fP &)"
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.RI "QPolygonF \fBpoints\fP () const "
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.RI "\fBQwtSpline\fP ()"
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.RI "\fBQwtSpline\fP (const \fBQwtSpline\fP &)"
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.RI "void \fBreset\fP ()"
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.RI "bool \fBsetPoints\fP (const QPolygonF &points)"
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.RI "void \fBsetSplineType\fP (\fBSplineType\fP)"
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.RI "\fBSplineType\fP \fBsplineType\fP () const "
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.RI "double \fBvalue\fP (double x) const "
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.RI "\fB~QwtSpline\fP ()"
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.SS "Protected Member Functions"

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.RI "bool \fBbuildNaturalSpline\fP (const QPolygonF &)"
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.RI "bool \fBbuildPeriodicSpline\fP (const QPolygonF &)"
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.SS "Protected Attributes"

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.RI "PrivateData * \fBd_data\fP"
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.SH "Detailed Description"
.PP 
A class for spline interpolation. 

The \fBQwtSpline\fP class is used for cubical spline interpolation. Two types of splines, natural and periodic, are supported.
.PP
\fBUsage:\fP
.RS 4

.PD 0

.IP "1." 4
First call \fBsetPoints()\fP to determine the spline coefficients for a tabulated function y(x). 
.IP "2." 4
After the coefficients have been set up, the interpolated function value for an argument x can be determined by calling \fBQwtSpline::value()\fP. 
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.RE
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\fBExample:\fP
.RS 4

.PP
.nf
#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;
}

.fi
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.RE
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.SH "Member Enumeration Documentation"
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.SS "enum \fBQwtSpline::SplineType\fP"
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Spline type. 
.SH "Constructor & Destructor Documentation"
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.SS "QwtSpline::QwtSpline ()"
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Constructor. 
.SS "QwtSpline::QwtSpline (const \fBQwtSpline\fP &other)"Copy constructor 
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\fBParameters:\fP
.RS 4
\fIother\fP Spline used for initilization 
.RE
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.SS "QwtSpline::~QwtSpline ()"
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Destructor. 
.SH "Member Function Documentation"
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.SS "bool QwtSpline::buildNaturalSpline (const QPolygonF &points)\fC [protected]\fP"
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Determines the coefficients for a natural spline. \fBReturns:\fP
.RS 4
true if successful 
.RE
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.SS "bool QwtSpline::buildPeriodicSpline (const QPolygonF &points)\fC [protected]\fP"
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Determines the coefficients for a periodic spline. \fBReturns:\fP
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true if successful 
.RE
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.SS "const QwtArray< double > & QwtSpline::coefficientsA () const"\fBReturns:\fP
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A coefficients 
.RE
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.SS "const QwtArray< double > & QwtSpline::coefficientsB () const"\fBReturns:\fP
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B coefficients 
.RE
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.SS "const QwtArray< double > & QwtSpline::coefficientsC () const"\fBReturns:\fP
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C coefficients 
.RE
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.SS "bool QwtSpline::isValid () const"
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True if valid. 
.SS "\fBQwtSpline\fP & QwtSpline::operator= (const \fBQwtSpline\fP &other)"Assignment operator 
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\fBParameters:\fP
.RS 4
\fIother\fP Spline used for initilization 
.RE
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.SS "QPolygonF QwtSpline::points () const"Return points passed by setPoints 
.SS "void QwtSpline::reset ()"
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Free allocated memory and set size to 0. 
.SS "bool QwtSpline::setPoints (const QPolygonF &points)"
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Calculate the spline coefficients. Depending on the value of \fIperiodic\fP, this function will determine the coefficients for a natural or a periodic spline and store them internally.
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\fBParameters:\fP
.RS 4
\fIpoints\fP Points 
.RE
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\fBReturns:\fP
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true if successful 
.RE
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\fBWarning:\fP
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The sequence of x (but not y) values has to be strictly monotone increasing, which means \fCpoints[i].x() < points[i+1].x()\fP. If this is not the case, the function will return false 
.RE
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.SS "void QwtSpline::setSplineType (\fBSplineType\fPsplineType)"Select the algorithm used for calculating the spline
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\fBParameters:\fP
.RS 4
\fIsplineType\fP Spline type 
.RE
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\fBSee also:\fP
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\fBsplineType()\fP 
.RE
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.SS "\fBQwtSpline::SplineType\fP QwtSpline::splineType () const"\fBReturns:\fP
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the spline type 
.RE
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\fBSee also:\fP
.RS 4
\fBsetSplineType()\fP 
.RE
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.SS "double QwtSpline::value (doublex) const"Calculate the interpolated function value corresponding to a given argument x. 

.SH "Author"
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