Package nl.tudelft.simulation.jstats.distributions

Class DistExponential

java.lang.Object

nl.tudelft.simulation.jstats.distributions.Dist

nl.tudelft.simulation.jstats.distributions.DistContinuous

nl.tudelft.simulation.jstats.distributions.DistExponential

All Implemented Interfaces:

Serializable

public class DistExponential
extends DistContinuous

The Exponential distribution. For more information on this distribution see https://mathworld.wolfram.com/ExponentialDistribution.html
The exponential distribution describes the interarrival times of entities to a system that occur randomly at a constant rate. The exponential distribution here is characterized by the mean interarrival time, but can also be characterized by this rate parameter λ; mean = 1 / λ.

Copyright (c) 2002-2023 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://simulation.tudelft.nl. The DSOL project is distributed under a three-clause BSD-style license, which can be found at https://https://simulation.tudelft.nl/dsol/docs/latest/license.html.

Author:

Peter Jacobs , Alexander Verbraeck

See Also:

Serialized Form

Field Summary

Fields inherited from class nl.tudelft.simulation.jstats.distributions.Dist

stream

Constructor Summary

Constructors

Constructor	Description
DistExponential(StreamInterface stream, double mean)	constructs a new exponential function.

Method Summary

Modifier and Type	Method	Description
double	draw()	draws the next stream value according to the probability of this this distribution.
double	getMean()
double	getProbabilityDensity(double x)	returns the probability density value of a value x.
String	toString()

Methods inherited from class nl.tudelft.simulation.jstats.distributions.Dist

getStream, setStream

Methods inherited from class java.lang.Object

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

Constructor Detail

DistExponential

public DistExponential(StreamInterface stream,
                       double mean)

constructs a new exponential function. The exponential distribution describes the interarrival times of entities to a system that occur randomly at a constant rate. The exponential distribution can also be characterized by this rate parameter λ; mean = 1 / λ.

Parameters:

stream - StreamInterface; the random number stream

mean - double; the mean (mean > 0) value of the exponential distribution. The exponential distribution can also be characterized by the rate parameter λ; mean = 1 / λ

Throws:

IllegalArgumentException - in case mean <= 0

Method Detail

draw

public double draw()

draws the next stream value according to the probability of this this distribution.

Specified by:

draw in class DistContinuous

Returns:

the next double value drawn.

getProbabilityDensity

public double getProbabilityDensity(double x)

returns the probability density value of a value x.

Specified by:

getProbabilityDensity in class DistContinuous

Parameters:

x - double; the value for which the density function needs to be calculated

Returns:

double; the probability density for value x

getMean

public double getMean()

Returns:

mean

toString

public String toString()

Overrides:

toString in class Object