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

java.lang.Object
  extended by org.apache.mahout.math.function.DoubleFunction
      extended by org.apache.mahout.math.jet.random.AbstractDistribution
          extended by org.apache.mahout.math.jet.random.AbstractContinousDistribution
              extended by org.apache.mahout.math.jet.random.Exponential
All Implemented Interfaces:
IntFunction

public class Exponential
extends AbstractContinousDistribution


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


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