Package net.algart.math.functions

Class PowerFunc

java.lang.Object

net.algart.math.functions.PowerFunc

All Implemented Interfaces:

Func

Direct Known Subclasses:

PowerFunc.Updatable

public abstract class PowerFunc
extends Object
implements Func

Power function: f(x₀, x₁) = scale*x₀^x₁ or f(x₀) = scale*x₀^c, where c and scale are constants. More precisely, the result of this function is:

• scale * Math.pow(x[0], x[1]) or scale * Math.pow(x[0], c) for the instance returned by getBinaryInstance(double scale) or getInstance(double c, double scale) methods;
• scale * StrictMath.pow(x[0], x[1]) or scale * StrictMath.pow(x[0], c) for the instance returned by getStrictBinaryInstance(double scale) or getStrictInstance(double c, double scale) methods.

The get(double...) method of the instance of this class requires at least 2 or 1 arguments (for the cases x₀^x₁ and x₀^c correspondingly) and throws IndexOutOfBoundsException if the number of arguments is less. In a case of using getStrictBinaryInstance(double scale) / getStrictInstance(double c, double scale) methods, all calculations are performed with help of StrictMath class, so the result is absolutely identical on all platforms.

This class is immutable and thread-safe: there are no ways to modify settings of the created instance.

Author:

Daniel Alievsky

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	PowerFunc.Updatable	Updatable extension of the power function with one argument.

Field Summary

Fields inherited from interface net.algart.math.functions.Func

ABS, ABS_DIFF, HALF_X_MINUS_Y, HALF_X_PLUS_Y, HALF_Y_MINUS_X, IDENTITY, MAX, MIN, POSITIVE_DIFF, REVERSE, SELECT, SELECT_FROM_8_DIRECTIONS_2D, SELECT_IF_GREATER, SELECT_IF_GREATER_OR_EQUAL, SHIFTS_ALONG_8_DIRECTIONS_2D, UPDATABLE_IDENTITY, X_MINUS_Y, X_PLUS_Y, Y_MINUS_X

Method Summary

Modifier and Type	Method	Description
abstract double	get()	Equivalent to get(new double[0]).
abstract double	get(double x0)	Equivalent to get(new double[] {x0}).
abstract double	get(double... x)	Returns the result of this function for the given arguments: f(x0, x1, ..., xx.length-1).
abstract double	get(double x0, double x1)	Equivalent to get(new double[] {x0, x1}).
abstract double	get(double x0, double x1, double x2)	Equivalent to get(new double[] {x0, x1, x2}).
static PowerFunc	getBinaryInstance(double scale)	Returns an instance of this class, a case of binary function scale*x0x1, using Math.pow method.
static PowerFunc	getInstance(double c)	Returns an instance of this class, a case of unary function x0c, using Math.pow method.
static PowerFunc	getInstance(double c, double scale)	Returns an instance of this class, a case of unary function scale*x0c, using Math.pow method.
static PowerFunc	getStrictBinaryInstance(double scale)	Returns an instance of this class, a case of binary function scale*x0x1, using StrictMath.pow method.
static PowerFunc	getStrictInstance(double c)	Returns an instance of this class, a case of unary function x0c, using StrictMath.pow method.
static PowerFunc	getStrictInstance(double c, double scale)	Returns an instance of this class, a case of unary function scale*x0c, using StrictMath.pow method.
static PowerFunc.Updatable	getUpdatableInstance(double c, double scale)	Returns an instance of the updatable version of this class, a case of unary function scale*x0c, using Math.pow method.
static PowerFunc.Updatable	getUpdatableStrictInstance(double c, double scale)	Returns an instance of the updatable version of this class, a case of unary function scale*x0c, using StrictMath.pow method.
String	toString()	Returns a brief string description of this object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.algart.math.functions.Func

get

Method Details

getBinaryInstance

public static PowerFunc getBinaryInstance(double scale)

Returns an instance of this class, a case of binary function scale*x₀^x₁, using Math.pow method.

Parameters:

scale - the constant scale.

Returns:

an instance of this class, a case of binary function, using Math.pow method.

getStrictBinaryInstance

public static PowerFunc getStrictBinaryInstance(double scale)

Returns an instance of this class, a case of binary function scale*x₀^x₁, using StrictMath.pow method.

Parameters:

scale - the constant scale.

Returns:

an instance of this class, a case of binary function, using StrictMath.pow method.

getInstance

public static PowerFunc getInstance(double c,
 double scale)

Returns an instance of this class, a case of unary function scale*x₀^c, using Math.pow method.

This method returns special optimized versions of this class for several popular values of cargument. In particular, there are optimized version for c = 1.0, 2.0, 3.0, 0.5, 1.0/3.0.

Parameters:

c - the constant c.

scale - the constant scale.

Returns:

an instance of this class, a case of unary function, using Math.pow method.

getInstance

public static PowerFunc getInstance(double c)

Returns an instance of this class, a case of unary function x₀^c, using Math.pow method.

Equivalent to getInstance(c,1.0).

Parameters:

c - the constant c.

Returns:

an instance of this class, a case of unary function, using Math.pow method.

getStrictInstance

public static PowerFunc getStrictInstance(double c,
 double scale)

Returns an instance of this class, a case of unary function scale*x₀^c, using StrictMath.pow method.

This method returns special optimized versions of this class for several popular values of cargument. In particular, there are optimized version for c = 1.0, 2.0, 3.0, 0.5, 1.0/3.0.

Parameters:

c - the constant c.

scale - the constant scale.

Returns:

an instance of this class, a case of unary function, using StrictMath.pow method.

getStrictInstance

public static PowerFunc getStrictInstance(double c)

Returns an instance of this class, a case of unary function x₀^c, using StrictMath.pow method.

Equivalent to getStrictInstance(c,1.0).

Parameters:

c - the constant c.

Returns:

an instance of this class, a case of unary function, using StrictMath.pow method.

getUpdatableInstance

public static PowerFunc.Updatable getUpdatableInstance(double c,
 double scale)

Returns an instance of the updatable version of this class, a case of unary function scale*x₀^c, using Math.pow method.

This method returns special optimized versions of this class for several popular values of cargument. In particular, there are optimized version for c = 1.0, 2.0, 3.0, 0.5, 1.0/3.0.

Parameters:

c - the constant c.

scale - the constant scale.

Returns:

an instance of this class, a case of unary function, using Math.pow method.

getUpdatableStrictInstance

public static PowerFunc.Updatable getUpdatableStrictInstance(double c,
 double scale)

Returns an instance of the updatable version of this class, a case of unary function scale*x₀^c, using StrictMath.pow method.

This method returns special optimized versions of this class for several popular values of cargument. In particular, there are optimized version for c = 1.0, 2.0, 3.0, 0.5, 1.0/3.0.

Parameters:

c - the constant c.

scale - the constant scale.

Returns:

an instance of this class, a case of unary function, using StrictMath.pow method.

get

public abstract double get(double... x)

Description copied from interface: Func

Returns the result of this function for the given arguments: f(x₀, x₁, ..., x_x.length-1).

This method must not change the values of x elements!

Specified by:

get in interface Func

Parameters:

x - the function arguments.

Returns:

the function result.

get

public abstract double get()

Description copied from interface: Func

Equivalent to get(new double[0]). Provides better performance because it does not require Java array creation.

Specified by:

get in interface Func

Returns:

the function result.

get

public abstract double get(double x0)

Description copied from interface: Func

Equivalent to get(new double[] {x0}). Provides better performance because it does not require Java array creation.

Specified by:

get in interface Func

Parameters:

x0 - the function argument.

Returns:

the function result.

get

public abstract double get(double x0,
 double x1)

Description copied from interface: Func

Equivalent to get(new double[] {x0, x1}). Provides better performance because it does not require Java array creation.

Specified by:

get in interface Func

Parameters:

x0 - the first function argument.

x1 - the second function argument.

Returns:

the function result.

get

public abstract double get(double x0,
 double x1,
 double x2)

Description copied from interface: Func

Equivalent to get(new double[] {x0, x1, x2}). Provides better performance because it does not require Java array creation.

Specified by:

get in interface Func

Parameters:

x0 - the first function argument.

x1 - the second function argument.

x2 - the third function argument.

Returns:

the function result.

toString

public String toString()

Returns a brief string description of this object.

Overrides:

toString in class Object

Returns:

a brief string description of this object.