QwtSplinePolynomial - Man Page
A cubic polynomial without constant term.
Synopsis
#include <qwt_spline_polynomial.h>
Public Member Functions
QwtSplinePolynomial (double c3=0.0, double c2=0.0, double c1=0.0)
Constructor.
bool operator== (const QwtSplinePolynomial &) const
bool operator!= (const QwtSplinePolynomial &) const
double valueAt (double x) const
double slopeAt (double x) const
double curvatureAt (double x) const
Static Public Member Functions
static QwtSplinePolynomial fromSlopes (const QPointF &p1, double m1, const QPointF &p2, double m2)
static QwtSplinePolynomial fromSlopes (double x, double y, double m1, double m2)
static QwtSplinePolynomial fromCurvatures (const QPointF &p1, double cv1, const QPointF &p2, double cv2)
static QwtSplinePolynomial fromCurvatures (double dx, double dy, double cv1, double cv2)
Public Attributes
double c3
coefficient of the cubic summand
double c2
coefficient of the quadratic summand
double c1
coefficient of the linear summand
Detailed Description
A cubic polynomial without constant term.
QwtSplinePolynomial is a 3rd degree polynomial of the form: y = c3 * x³ + c2 * x² + c1 * x;
QwtSplinePolynomial is usually used in combination with polygon interpolation, where it is not necessary to store a constant term ( c0 ), as the translation is known from the corresponding polygon points.
- See also
QwtSplineC1
Definition at line 30 of file qwt_spline_polynomial.h.
Constructor & Destructor Documentation
QwtSplinePolynomial::QwtSplinePolynomial (double a3 = 0.0, double a2 = 0.0, double a1 = 0.0) [inline]
Constructor.
- Parameters
a3 Coefficient of the cubic summand
a2 Coefficient of the quadratic summand
a1 Coefficient of the linear summand
Definition at line 77 of file qwt_spline_polynomial.h.
Member Function Documentation
double QwtSplinePolynomial::curvatureAt (double x) const [inline]
Calculate the value of the second derivate of a polynomial for a given x
- Parameters
x Parameter
- Returns
Curvature at x
Definition at line 130 of file qwt_spline_polynomial.h.
QwtSplinePolynomial QwtSplinePolynomial::fromCurvatures (const QPointF & p1, double cv1, const QPointF & p2, double cv2) [inline], [static]
Find the coefficients for the polynomial including 2 points with specific values for the 2nd derivates at these points.
- Parameters
p1 First point
cv1 Value of the second derivate at p1
p2 Second point
cv2 Value of the second derivate at p2- Returns
Coefficients of the polynomials
- Note
The missing constant term of the polynomial is p1.y()
Definition at line 185 of file qwt_spline_polynomial.h.
QwtSplinePolynomial QwtSplinePolynomial::fromCurvatures (double dx, double dy, double cv1, double cv2) [inline], [static]
Find the coefficients for the polynomial from the offset between 2 points and specific values for the 2nd derivates at these points.
- Parameters
dx X-offset
dy Y-offset
cv1 Value of the second derivate at p1
cv2 Value of the second derivate at p2- Returns
Coefficients of the polynomials
Definition at line 202 of file qwt_spline_polynomial.h.
QwtSplinePolynomial QwtSplinePolynomial::fromSlopes (const QPointF & p1, double m1, const QPointF & p2, double m2) [inline], [static]
Find the coefficients for the polynomial including 2 points with specific values for the 1st derivates at these points.
- Parameters
p1 First point
m1 Value of the first derivate at p1
p2 Second point
m2 Value of the first derivate at p2- Returns
Coefficients of the polynomials
- Note
The missing constant term of the polynomial is p1.y()
Definition at line 147 of file qwt_spline_polynomial.h.
QwtSplinePolynomial QwtSplinePolynomial::fromSlopes (double dx, double dy, double m1, double m2) [inline], [static]
Find the coefficients for the polynomial from the offset between 2 points and specific values for the 1st derivates at these points.
- Parameters
dx X-offset
dy Y-offset
m1 Value of the first derivate at p1
m2 Value of the first derivate at p2- Returns
Coefficients of the polynomials
Definition at line 164 of file qwt_spline_polynomial.h.
bool QwtSplinePolynomial::operator!= (const QwtSplinePolynomial & other) const [inline]
- Parameters
other Other polynomial
- Returns
true, when the polynomials have different coefficients
Definition at line 97 of file qwt_spline_polynomial.h.
bool QwtSplinePolynomial::operator== (const QwtSplinePolynomial & other) const [inline]
- Parameters
other Other polynomial
- Returns
true, when both polynomials have the same coefficients
Definition at line 88 of file qwt_spline_polynomial.h.
double QwtSplinePolynomial::slopeAt (double x) const [inline]
Calculate the value of the first derivate of a polynomial for a given x
- Parameters
x Parameter
- Returns
Slope at x
Definition at line 119 of file qwt_spline_polynomial.h.
double QwtSplinePolynomial::valueAt (double x) const [inline]
Calculate the value of a polynomial for a given x
- Parameters
x Parameter
- Returns
Value at x
Definition at line 108 of file qwt_spline_polynomial.h.
Author
Generated automatically by Doxygen for Qwt User's Guide from the source code.