Package org.faceless.graph.math

Class Polynomial

java.lang.Object

org.faceless.graph.math.Curve

org.faceless.graph.math.FunctionCurve

org.faceless.graph.math.Polynomial

public class Polynomial
extends FunctionCurve

Represents a Polynomial Curve of any degree > 2. A polynomial can be fitted to a DataCurve to give a smoother curve, but owing to the nature of polynomial functions this may result in some large "wiggles" in the curve (we suspect this is not the correct mathematical term). Generally the best choice for a curve fitting function is a Spline curve.

Constructor Summary

Constructors

Constructor	Description
Polynomial(int order, double[] x)	Create a polynomial of the specified order with the specified coefficients.

Method Summary

Modifier and Type	Method	Description
static Polynomial	fit(double[] xvals, double[] yvals)	Return a new polynomial that is fitted to the specified array of X and Y values within the tolerance set by setFitTolerance.
static Polynomial	fit(int order, double[] xvals, double[] yvals)	Return a new polynomial of the specified order that is fitted to the specified array of X and Y values within the tolerance set by setFitTolerance.
static Polynomial	fit(DataCurve d)	Return a new polynomial that is fitted to the specified data curve within the tolerance set by setFitTolerance.
double	get(double x)	Return the value of this curve at the specified X position.
double	maxMatchError(double[] xvals, double[] yvals)	Return the maximum distance from the specified set of X and Y values of this polynomial.
static void	setFitTolerance(double v)	When fitting a polynomial to a curve, the Fit Tolerance is the maximum distance from each point the polynomial can be, as a proportion of the value of the point.
java.lang.String	toString()

Methods inherited from class org.faceless.graph.math.FunctionCurve

getMax, getMin, point, steps

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Polynomial

public Polynomial(int order,
                  double[] x)

Create a polynomial of the specified order with the specified coefficients. For example, passing in the order 2 and the array [1, 2, 1] creates a polynomial representing x^2 + 2x + 1

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

get

public double get(double x)

Description copied from class: Curve

Return the value of this curve at the specified X position. If the curve has no value at this point (i.e. x<curve min or x>curve max) return Double.NaN

Specified by:

get in class Curve

setFitTolerance

public static void setFitTolerance(double v)

When fitting a polynomial to a curve, the Fit Tolerance is the maximum distance from each point the polynomial can be, as a proportion of the value of the point. Lower values give more accurate curves but take more time to fit. The default is 0.05.

fit

public static Polynomial fit(DataCurve d)

Return a new polynomial that is fitted to the specified data curve within the tolerance set by setFitTolerance.

fit

public static Polynomial fit(double[] xvals,
                             double[] yvals)

Return a new polynomial that is fitted to the specified array of X and Y values within the tolerance set by setFitTolerance.

fit

public static Polynomial fit(int order,
                             double[] xvals,
                             double[] yvals)

Return a new polynomial of the specified order that is fitted to the specified array of X and Y values within the tolerance set by setFitTolerance.

maxMatchError

public double maxMatchError(double[] xvals,
                            double[] yvals)

Return the maximum distance from the specified set of X and Y values of this polynomial.