JSci.maths.statistics
Class WeibullDistribution

java.lang.Object
  extended by JSci.maths.statistics.ProbabilityDistribution
      extended by JSci.maths.statistics.WeibullDistribution

public final class WeibullDistribution
extends ProbabilityDistribution

The WeibullDistribution class provides an object for encapsulating Weibull distributions.


Constructor Summary
WeibullDistribution(double sh)
          Constructs a Weibull distribution.
 
Method Summary
 double cumulative(double X)
          Cumulative Weibull distribution function.
 double getMean()
          Returns the mean.
 double getShapeParameter()
          Returns the shape parameter.
 double getVariance()
          Returns the variance.
 double inverse(double probability)
          Inverse of the cumulative Weibull distribution function.
 double probability(double X)
          Probability density function of a Weibull distribution.
 
Methods inherited from class JSci.maths.statistics.ProbabilityDistribution
checkRange, checkRange, findRoot
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

WeibullDistribution

public WeibullDistribution(double sh)
Constructs a Weibull distribution.

Parameters:
sh - the shape.
Method Detail

getShapeParameter

public double getShapeParameter()
Returns the shape parameter.


getMean

public double getMean()
Returns the mean.


getVariance

public double getVariance()
Returns the variance.


probability

public double probability(double X)
Probability density function of a Weibull distribution. P(X) = s Xs-1 exp(-Xs).

Specified by:
probability in class ProbabilityDistribution
Parameters:
X - should be integer-valued.
Returns:
the probability that a stochastic variable x has the value X, i.e. P(x=X).

cumulative

public double cumulative(double X)
Cumulative Weibull distribution function.

Specified by:
cumulative in class ProbabilityDistribution
Parameters:
X - should be integer-valued.
Returns:
the probability that a stochastic variable x is less then X, i.e. P(x<X).

inverse

public double inverse(double probability)
Inverse of the cumulative Weibull distribution function.

Specified by:
inverse in class ProbabilityDistribution
Returns:
the value X for which P(x<X).