org.apache.commons.math3.analysis

## Class FunctionUtils

- java.lang.Object
- - org.apache.commons.math3.analysis.FunctionUtils

    public class FunctionUtils
    extends java.lang.Object

Utilities for manipulating function objects.

Since:
  3.0
Version:
  $Id: FunctionUtils.java 1401837 2012-10-24 19:39:45Z luc $

### Constructor Summary

Constructors
`private` `FunctionUtils()` Class only contains static methods.

### Method Summary

Methods
`static DifferentiableUnivariateFunction` `add(DifferentiableUnivariateFunction... f)` Deprecated. as of 3.1 replaced by `add(UnivariateDifferentiableFunction...)`
`static UnivariateDifferentiableFunction` `add(UnivariateDifferentiableFunction... f)` Adds functions.
`static UnivariateFunction` `add(UnivariateFunction... f)` Adds functions.
`static MultivariateFunction` `collector(BivariateFunction combiner, double initialValue)` Returns a MultivariateFunction h(x[]) defined by
`static MultivariateFunction` `collector(BivariateFunction combiner, UnivariateFunction f, double initialValue)` Returns a MultivariateFunction h(x[]) defined by
`static UnivariateFunction` `combine(BivariateFunction combiner, UnivariateFunction f, UnivariateFunction g)` Returns the univariate function `h(x) = combiner(f(x), g(x))`.
`static DifferentiableUnivariateFunction` `compose(DifferentiableUnivariateFunction... f)` Deprecated. as of 3.1 replaced by `compose(UnivariateDifferentiableFunction...)`
`static UnivariateDifferentiableFunction` `compose(UnivariateDifferentiableFunction... f)` Composes functions.
`static UnivariateFunction` `compose(UnivariateFunction... f)` Composes functions.
`static UnivariateFunction` `fix1stArgument(BivariateFunction f, double fixed)` Creates a unary function by fixing the first argument of a binary function.
`static UnivariateFunction` `fix2ndArgument(BivariateFunction f, double fixed)` Creates a unary function by fixing the second argument of a binary function.
`static DifferentiableUnivariateFunction` `multiply(DifferentiableUnivariateFunction... f)` Deprecated. as of 3.1 replaced by `multiply(UnivariateDifferentiableFunction...)`
`static UnivariateDifferentiableFunction` `multiply(UnivariateDifferentiableFunction... f)` Multiplies functions.
`static UnivariateFunction` `multiply(UnivariateFunction... f)` Multiplies functions.
`static double[]` `sample(UnivariateFunction f, double min, double max, int n)` Samples the specified univariate real function on the specified interval.
`static DifferentiableMultivariateFunction` `toDifferentiableMultivariateFunction(MultivariateDifferentiableFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
`static DifferentiableMultivariateVectorFunction` `toDifferentiableMultivariateVectorFunction(MultivariateDifferentiableVectorFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateVectorFunction` interface itself is deprecated
`static DifferentiableUnivariateFunction` `toDifferentiableUnivariateFunction(UnivariateDifferentiableFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableUnivariateFunction` interface itself is deprecated
`static MultivariateDifferentiableFunction` `toMultivariateDifferentiableFunction(DifferentiableMultivariateFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
`static MultivariateDifferentiableVectorFunction` `toMultivariateDifferentiableVectorFunction(DifferentiableMultivariateVectorFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
`static UnivariateDifferentiableFunction` `toUnivariateDifferential(DifferentiableUnivariateFunction f)` Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableUnivariateFunction` interface itself is deprecated

### Methods inherited from class java.lang.Object

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

### Constructor Detail

#### FunctionUtils

    private FunctionUtils()

Class only contains static methods.

### Method Detail

#### compose

    public static UnivariateFunction compose(UnivariateFunction... f)

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

Parameters:
  `f` - List of functions.
Returns:
  the composite function.

#### compose

    public static UnivariateDifferentiableFunction compose(UnivariateDifferentiableFunction... f)

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

Parameters:
  `f` - List of functions.
Returns:
  the composite function.
Since:
  3.1

#### compose

    public static DifferentiableUnivariateFunction compose(DifferentiableUnivariateFunction... f)

Deprecated. as of 3.1 replaced by `compose(UnivariateDifferentiableFunction...)`
Composes functions.
The functions in the argument list are composed sequentially, in the given order. For example, compose(f1,f2,f3) acts like f1(f2(f3(x))).

Parameters:
  `f` - List of functions.
Returns:
  the composite function.

#### add

    public static UnivariateFunction add(UnivariateFunction... f)

Adds functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the sum of the functions.

#### add

    public static UnivariateDifferentiableFunction add(UnivariateDifferentiableFunction... f)

Adds functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the sum of the functions.
Since:
  3.1

#### add

    @Deprecated
    public static DifferentiableUnivariateFunction add(DifferentiableUnivariateFunction... f)

Deprecated. as of 3.1 replaced by `add(UnivariateDifferentiableFunction...)`
Adds functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the sum of the functions.

#### multiply

    public static UnivariateFunction multiply(UnivariateFunction... f)

Multiplies functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the product of the functions.

#### multiply

    public static UnivariateDifferentiableFunction multiply(UnivariateDifferentiableFunction... f)

Multiplies functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the product of the functions.
Since:
  3.1

#### multiply

    public static DifferentiableUnivariateFunction multiply(DifferentiableUnivariateFunction... f)

Deprecated. as of 3.1 replaced by `multiply(UnivariateDifferentiableFunction...)`
Multiplies functions.

Parameters:
  `f` - List of functions.
Returns:
  a function that computes the product of the functions.

#### combine

    public static UnivariateFunction combine(BivariateFunction combiner,
                             UnivariateFunction f,
                             UnivariateFunction 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 MultivariateFunction collector(BivariateFunction combiner,
                                 UnivariateFunction f,
                                 double initialValue)

Returns a MultivariateFunction 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 MultivariateFunction collector(BivariateFunction combiner,
                                 double initialValue)

Returns a MultivariateFunction 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 UnivariateFunction fix1stArgument(BivariateFunction f,
                                    double fixed)

Creates 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 UnivariateFunction fix2ndArgument(BivariateFunction f,
                                    double fixed)

Creates 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)

#### sample

    public static double[] sample(UnivariateFunction f,
                  double min,
                  double max,
                  int n)

Samples the specified univariate real function on the specified interval.
The interval is divided equally into `n` sections and sample points are taken from `min` to `max - (max - min) / n`; therefore `f` is not sampled at the upper bound `max`.

Parameters:
  `f` - Function to be sampled
  `min` - Lower bound of the interval (included).
  `max` - Upper bound of the interval (excluded).
  `n` - Number of sample points.
Returns:
  the array of samples.
Throws:
  `NumberIsTooLargeException` - if the lower bound `min` is greater than, or equal to the upper bound `max`.
  `NotStrictlyPositiveException` - if the number of sample points `n` is negative.

#### toDifferentiableUnivariateFunction

    @Deprecated
    public static DifferentiableUnivariateFunction toDifferentiableUnivariateFunction(UnivariateDifferentiableFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableUnivariateFunction` interface itself is deprecated
Convert a `UnivariateDifferentiableFunction` into a `DifferentiableUnivariateFunction`.

Parameters:
  `f` - function to convert
Returns:
  converted function

#### toUnivariateDifferential

    @Deprecated
    public static UnivariateDifferentiableFunction toUnivariateDifferential(DifferentiableUnivariateFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableUnivariateFunction` interface itself is deprecated
Convert a `DifferentiableUnivariateFunction` into a `UnivariateDifferentiableFunction`.

Note that the converted function is able to handle `DerivativeStructure` up to order one. If the function is called with higher order, a `NumberIsTooLargeException` will be thrown.

Parameters:
  `f` - function to convert
Returns:
  converted function

#### toDifferentiableMultivariateFunction

    @Deprecated
    public static DifferentiableMultivariateFunction toDifferentiableMultivariateFunction(MultivariateDifferentiableFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
Convert a `MultivariateDifferentiableFunction` into a `DifferentiableMultivariateFunction`.

Parameters:
  `f` - function to convert
Returns:
  converted function

#### toMultivariateDifferentiableFunction

    @Deprecated
    public static MultivariateDifferentiableFunction toMultivariateDifferentiableFunction(DifferentiableMultivariateFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
Convert a `DifferentiableMultivariateFunction` into a `MultivariateDifferentiableFunction`.

Note that the converted function is able to handle `DerivativeStructure` elements that all have the same number of free parameters and order, and with order at most 1. If the function is called with inconsistent numbers of free parameters or higher order, a `DimensionMismatchException` or a `NumberIsTooLargeException` will be thrown.

Parameters:
  `f` - function to convert
Returns:
  converted function

#### toDifferentiableMultivariateVectorFunction

    @Deprecated
    public static DifferentiableMultivariateVectorFunction toDifferentiableMultivariateVectorFunction(MultivariateDifferentiableVectorFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateVectorFunction` interface itself is deprecated
Convert a `MultivariateDifferentiableVectorFunction` into a `DifferentiableMultivariateVectorFunction`.

Parameters:
  `f` - function to convert
Returns:
  converted function

#### toMultivariateDifferentiableVectorFunction

    @Deprecated
    public static MultivariateDifferentiableVectorFunction toMultivariateDifferentiableVectorFunction(DifferentiableMultivariateVectorFunction f)

Deprecated. this conversion method is temporary in version 3.1, as the `DifferentiableMultivariateFunction` interface itself is deprecated
Convert a `DifferentiableMultivariateVectorFunction` into a `MultivariateDifferentiableVectorFunction`.

Note that the converted function is able to handle `DerivativeStructure` elements that all have the same number of free parameters and order, and with order at most 1. If the function is called with inconsistent numbers of free parameters or higher order, a `DimensionMismatchException` or a `NumberIsTooLargeException` will be thrown.

Parameters:
  `f` - function to convert
Returns:
  converted function