uk.ac.starlink.dpac.math

Class FuncUtils

java.lang.Object

uk.ac.starlink.dpac.math.FuncUtils

public class FuncUtils
extends Object

Utility methods associated with functions. This class contains only static methods.

Since:

15 Mar 2018

Author:

Mark Taylor

Method Summary

Modifier and Type	Method and Description
static double	findValueMonotonic(Function f, double xlo, double xhi, double y0, double ytol) Locates the X value where a supplied monotonically non-decreasing function is within a specified tolerance of a given Y value.
static Function	interpolateLinear(NumericFunction nf) Returns a function which represents an interpolated representation of the given sample set, using linear interpolation.
static Function	interpolateQuadratic(NumericFunction nf) Returns a function which represents an interpolated representation of the given sample set, using quadratic interpolation with Legendre polynomials.
static Function	interpolateSpline(NumericFunction nf) Returns a function which represents an interpolated representation of the given sample set, using splines.

Methods inherited from class java.lang.Object

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

Method Detail

interpolateQuadratic

public static Function interpolateQuadratic(NumericFunction nf)

Returns a function which represents an interpolated representation of the given sample set, using quadratic interpolation with Legendre polynomials.

Parameters:

nf - input numeric function

Returns:

interpolated version of function

interpolateSpline

public static Function interpolateSpline(NumericFunction nf)

Returns a function which represents an interpolated representation of the given sample set, using splines.

Parameters:

nf - input numeric function

Returns:

interpolated version of function

interpolateLinear

public static Function interpolateLinear(NumericFunction nf)

Returns a function which represents an interpolated representation of the given sample set, using linear interpolation.

Parameters:

nf - input numeric function

Returns:

interpolated version of function

findValueMonotonic

public static double findValueMonotonic(Function f,
                                        double xlo,
                                        double xhi,
                                        double y0,
                                        double ytol)

Locates the X value where a supplied monotonically non-decreasing function is within a specified tolerance of a given Y value. The bisection method is used. Behaviour is undefined if the supplied function is not monotonic.

Parameters:

f - monotonic function

xlo - lowest X value to consider

xhi - highest X value to consider

y0 - required Y value

ytol - tolerance in Y

Returns:

X value corresonding to y0, or NaN if it's not in range