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net.algart.math.functions
Class LogFunc

java.lang.Object
  extended by net.algart.math.functions.LogFunc
All Implemented Interfaces:
Func
public abstract class LogFunc
extends java.lang.Object
implements Func

Logarithm function: f(x0) = logb(x0) (b is the base of the logarithm). More precisely, the result of this function is Math.log(x[0])*(1.0/Math.log(b)) for the instance returned by getInstance(b) method or StrictMath.log(x[0])*(1.0/Math.log(b)) for the instance returned by getStrictInstance(b) method. The get(double...) method of the instance of this class requires at least 1 argument and throws IndexOutOfBoundsException if the number of arguments is 0.

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

AlgART Laboratory 2007-2013

Since:
JDK 1.5
Version:
1.2
Author:
Daniel Alievsky

Nested Class Summary
Modifier and Type Interface and Description
 
Nested classes/interfaces inherited from interface net.algart.math.functions.Func
Func.Updatable
 
Field Summary
Modifier and Type Field and Description
 
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 and Description
 double get()
          Equivalent to get(new double[0]).
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)
          Equivalent to get(new double[] {x0}).
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}).
abstract  double get(double x0, double x1, double x2, double x3)
          Equivalent to get(new double[] {x0, x1, x2, x3}).
static LogFunc getInstance(double b)
          Returns an instance of this class for the given logarithm base b using Math.log method.
static LogFunc getStrictInstance(double b)
          Returns an instance of this class for the given logarithm base b using StrictMath.log method.
 java.lang.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
 

Method Detail

getInstance

public static LogFunc getInstance(double b)
Returns an instance of this class for the given logarithm base b using Math.log method.

This method returns special optimized versions of this class for base=Math.E and base=10.0.

Parameters:
b - the base of the logarithm.
Returns:
an instance of this class using Math.log method.

getStrictInstance

public static LogFunc getStrictInstance(double b)
Returns an instance of this class for the given logarithm base b using StrictMath.log method.

This method returns special optimized versions of this class for base=Math.E and base=10.0.

Parameters:
b - the base of the logarithm.
Returns:
an instance of this class using StrictMath.log 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, ..., xx.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 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.

get

public abstract double get(double x0,
                           double x1,
                           double x2,
                           double x3)
Description copied from interface: Func
Equivalent to get(new double[] {x0, x1, x2, x3}). 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.
x3 - the fourth function argument.
Returns:
the function result.

toString

public java.lang.String toString()
Returns a brief string description of this object.

Overrides:
toString in class java.lang.Object
Returns:
a brief string description of this object.
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