org.apache.commons.math.analysis
Class FunctionUtils

java.lang.Object
  org.apache.commons.math.analysis.FunctionUtils

public class FunctionUtils
extends java.lang.Object

Utilities for manipulating function objects.

Since:

3.0

Version:

$Id$

Method Summary

static DifferentiableUnivariateRealFunction	add(DifferentiableUnivariateRealFunction... f) Add functions.
static UnivariateRealFunction	add(UnivariateRealFunction... f) Add functions.
static MultivariateRealFunction	collector(BivariateRealFunction combiner, double initialValue) Returns a MultivariateRealFunction h(x[]) defined by h(x[]) = combiner(...combiner(combiner(initialValue,x[0]),x[1])...)
static MultivariateRealFunction	collector(BivariateRealFunction combiner, UnivariateRealFunction f, double initialValue) Returns a MultivariateRealFunction h(x[]) defined by h(x[]) = combiner(...combiner(combiner(initialValue,f(x[0])),f(x[1]))...)
static UnivariateRealFunction	combine(BivariateRealFunction combiner, UnivariateRealFunction f, UnivariateRealFunction g) Returns the univariate function h(x) = combiner(f(x), g(x)).
static DifferentiableUnivariateRealFunction	compose(DifferentiableUnivariateRealFunction... f) Compose functions.
static UnivariateRealFunction	compose(UnivariateRealFunction... f) Compose functions.
static UnivariateRealFunction	fix1stArgument(BivariateRealFunction f, double fixed) Create a unary function by fixing the first argument of a binary function.
static UnivariateRealFunction	fix2ndArgument(BivariateRealFunction f, double fixed) Create a unary function by fixing the second argument of a binary function.
static DifferentiableUnivariateRealFunction	multiply(DifferentiableUnivariateRealFunction... f) Multiply functions.
static UnivariateRealFunction	multiply(UnivariateRealFunction... f) Multiply functions.

Methods inherited from class java.lang.Object

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

Method Detail

compose

public static UnivariateRealFunction compose(UnivariateRealFunction... f)

Compose functions. The functions in the argument list are composed sequentially, in the order given. For example, compose(f1,f2,f3) acts like f1(f2(f3(x))).

Parameters:

f - List of functions.

Returns:

the composite function.

compose

public static DifferentiableUnivariateRealFunction compose(DifferentiableUnivariateRealFunction... f)

Compose functions. The functions in the argument list are composed sequentially, in the order given. For example, compose(f1,f2,f3) acts like f1(f2(f3(x))).

Parameters:

f - List of functions.

Returns:

the composite function.

add

public static UnivariateRealFunction add(UnivariateRealFunction... f)

Add functions.

Parameters:

f - List of functions.

Returns:

a function that computes the sum of the functions.

add

public static DifferentiableUnivariateRealFunction add(DifferentiableUnivariateRealFunction... f)

Add functions.

Parameters:

f - List of functions.

Returns:

a function that computes the sum of the functions.

multiply

public static UnivariateRealFunction multiply(UnivariateRealFunction... f)

Multiply functions.

Parameters:

f - List of functions.

Returns:

a function that computes the product of the functions.

multiply

public static DifferentiableUnivariateRealFunction multiply(DifferentiableUnivariateRealFunction... f)

Multiply functions.

Parameters:

f - List of functions.

Returns:

a function that computes the product of the functions.

combine

public static UnivariateRealFunction combine(BivariateRealFunction combiner,
                                             UnivariateRealFunction f,
                                             UnivariateRealFunction g)

Returns the univariate function
h(x) = combiner(f(x), g(x)).

Parameters:

combiner - Combiner function.

f - Function.

g - Function.

Returns:

the composite function.

collector

public static MultivariateRealFunction collector(BivariateRealFunction combiner,
                                                 UnivariateRealFunction f,
                                                 double initialValue)

Returns a MultivariateRealFunction h(x[]) defined by

 
 h(x[]) = combiner(...combiner(combiner(initialValue,f(x[0])),f(x[1]))...),f(x[x.length-1]))
 

Parameters:

combiner - Combiner function.

f - Function.

initialValue - Initial value.

Returns:

a collector function.

collector

public static MultivariateRealFunction collector(BivariateRealFunction combiner,
                                                 double initialValue)

Returns a MultivariateRealFunction h(x[]) defined by

 
 h(x[]) = combiner(...combiner(combiner(initialValue,x[0]),x[1])...),x[x.length-1])
 

Parameters:

combiner - Combiner function.

initialValue - Initial value.

Returns:

a collector function.

fix1stArgument

public static UnivariateRealFunction fix1stArgument(BivariateRealFunction f,
                                                    double fixed)

Create a unary function by fixing the first argument of a binary function.

Parameters:

f - Binary function.

fixed - Value to which the first argument of f is set.

Returns:

the unary function h(x) = f(fixed, x)

fix2ndArgument

public static UnivariateRealFunction fix2ndArgument(BivariateRealFunction f,
                                                    double fixed)

Create a unary function by fixing the second argument of a binary function.

Parameters:

f - Binary function.

fixed - Value to which the second argument of f is set.

Returns:

the unary function h(x) = f(x, fixed)