cern.jet.random
Class Weibull

java.lang.Object
  |
  +--cern.colt.PersistentObject
        |
        +--cern.jet.random.AbstractDistribution
              |
              +--cern.jet.random.AbstractContinousDistribution
                    |
                    +--cern.jet.random.Weibull
All Implemented Interfaces:
java.lang.Cloneable, cern.colt.function.DoubleFunction, cern.colt.function.IntFunction, java.io.Serializable

public class Weibull
extends AbstractContinousDistribution

Weibull Distribution. See the math definition.

p(x) = shape/scale*(x/scale)^(shape-1)*exp{-(x/scale)^shape} for x >= scale, shape > 0.

Note that mean is infinite if shape <= 1 and variance is infinite if shape <= 2.

Instance methods operate on a user supplied uniform random number generator; they are unsynchronized.

Static methods operate on a default uniform random number generator; they are synchronized.

See Also:
Serialized Form

Field Summary
protected  double scale
           
protected  double shape
           
protected static Weibull shared
           
 
Fields inherited from class cern.jet.random.AbstractDistribution
randomGenerator
 
Constructor Summary
Weibull(double a, double b, RandomElement randomGenerator)
          Constructs a Pareto distribution.
 
Method Summary
 double cdf(double x)
          Returns the cumulative distribution function.
 double nextDouble()
          Returns a random number from the distribution.
 double nextDouble(double a, double b)
          Returns a random number from the distribution; bypasses the internal state.
 double pdf(double x)
          Returns the probability distribution function.
 void setState(double a, double b)
          Sets the parameters.
static double staticNextDouble(double a, double b)
          Returns a random number from the distribution with the given scale = k, and shape = alpha.
 java.lang.String toString()
          Returns a String representation of the receiver.
 
Methods inherited from class cern.jet.random.AbstractDistribution
apply, apply, clone, getRandomGenerator, makeDefaultGenerator, nextInt, setRandomGenerator
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

scale

protected double scale

shape

protected double shape

shared

protected static Weibull shared
Constructor Detail

Weibull

public Weibull(double a,
               double b,
               RandomElement randomGenerator)
Constructs a Pareto distribution.

Method Detail

cdf

public double cdf(double x)
Returns the cumulative distribution function.


nextDouble

public double nextDouble()
Returns a random number from the distribution.

Specified by:
nextDouble in class AbstractDistribution

nextDouble

public double nextDouble(double a,
                         double b)
Returns a random number from the distribution; bypasses the internal state.


pdf

public double pdf(double x)
Returns the probability distribution function.


setState

public void setState(double a,
                     double b)
Sets the parameters.


staticNextDouble

public static double staticNextDouble(double a,
                                      double b)
Returns a random number from the distribution with the given scale = k, and shape = alpha.


toString

public java.lang.String toString()
Returns a String representation of the receiver.

Overrides:
toString in class java.lang.Object