org.apache.mahout.math.jet.random

Class Exponential

java.lang.Object

org.apache.mahout.math.function.DoubleFunction

org.apache.mahout.math.jet.random.AbstractDistribution

org.apache.mahout.math.jet.random.AbstractContinousDistribution

org.apache.mahout.math.jet.random.Exponential

All Implemented Interfaces:

IntFunction

public class Exponential
extends AbstractContinousDistribution

Constructor Summary

Constructors

Constructor and Description
Exponential(double lambda, Random randomGenerator) Provides a negative exponential distribution given a rate parameter lambda and an underlying random number generator.

Method Summary

Methods

Modifier and Type	Method and Description
double	cdf(double x) Returns the cumulative distribution function.
double	nextDouble() Returns a random number from the distribution.
double	pdf(double x) Returns the value of the probability density function at a particular point.
void	setState(double lambda) Sets the rate parameter.
String	toString() Returns a String representation of the receiver.

Methods inherited from class org.apache.mahout.math.jet.random.AbstractContinousDistribution

nextInt

Methods inherited from class org.apache.mahout.math.jet.random.AbstractDistribution

apply, apply, getRandomGenerator, randomDouble, setRandomGenerator

Methods inherited from class org.apache.mahout.math.function.DoubleFunction

isDensifying

Methods inherited from class java.lang.Object

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

Constructor Detail

Exponential

public Exponential(double lambda,
           Random randomGenerator)

Provides a negative exponential distribution given a rate parameter lambda and an underlying random number generator. The mean of this distribution will be equal to 1/lambda.

Parameters:

lambda - The rate parameter of the distribution.

randomGenerator - The PRNG that is used to generate values.

Method Detail

cdf

public double cdf(double x)

Returns the cumulative distribution function.

Overrides:

cdf in class AbstractContinousDistribution

Parameters:

x - The point at which the cumulative distribution function is to be evaluated.

Returns:

Returns the integral from -infinity to x of the PDF, also known as the cumulative distribution function.

nextDouble

public double nextDouble()

Returns a random number from the distribution.

Specified by:

nextDouble in class AbstractDistribution

Returns:

A new sample from this distribution.

pdf

public double pdf(double x)

Returns the value of the probability density function at a particular point.

Overrides:

pdf in class AbstractContinousDistribution

Parameters:

x - The point at which the probability density function is to be evaluated.

Returns:

The value of the probability density function at the specified point.

setState

public void setState(double lambda)

Sets the rate parameter.

Parameters:

lambda - The new value of the rate parameter.

toString

public String toString()

Returns a String representation of the receiver.

Overrides:

toString in class Object