0000693: truncnormal can return negative values

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Date Submitted

Last Update

0000693

OMNeT++

simulation kernel

public

2013-12-08 19:38

2013-12-09 10:30

Reporter

woife

Assigned To

andras

Priority

normal

Severity

major

Reproducibility

always

Status

resolved

Resolution

fixed

Platform

OS Version

Product Version

4.3.1

Target Version

Fixed in Version

4.4

Summary

0000693: truncnormal can return negative values

Description

The documentation for the function truncnormal states the following:
"Normal distribution truncated to nonnegative values." [1]

There is a SimTime-version of truncnormal, and this version can return negative values:

-----------[ Code in OMNeT/include/distrib.h ------------------------------
/**
* Normal distribution truncated to nonnegative values.
* It is implemented with a loop that discards negative values until
* a nonnegative one comes. This means that the execution time is not bounded:
* a large negative mean with much smaller stddev is likely to result
* in a large number of iterations.
*
* The mean and stddev parameters serve as parameters to the normal
* distribution before truncation. The actual random variate returned
* will have a different mean and standard deviation.
*
* @param mean mean of the normal distribution
* @param stddev standard deviation of the normal distribution
* @param rng the underlying random number generator
*/
SIM_API double truncnormal(double mean, double stddev, int rng=0);

/**
* SimTime version of truncnormal(double,double,int), for convenience.
*/
inline SimTime truncnormal(SimTime mean, SimTime stddev, int rng=0) {return normal(mean.dbl(), stddev.dbl(), rng);}
------------------------------------------------------------------

The problem here is that the SimTime-version internally does not call truncnormal(), but the standard normal() function.

[1] http://www.omnetpp.org/doc/omnetpp/api/group__RandomNumbersCont.html#ge59607f50d297c0f8ce72b833c343c50 [^]

Additional Information

I don't know OMNeT well enough for the 'Category' where this bug fits, so I have chosen 'simulation kernel'.
Please adjust as appropriate.

Notes
(0000858) andras (administrator) 2013-12-09 10:30	Thanks for the report, came just in time to be included in OMNeT++ 4.4. It was a copy-paste bug, fixed.

Issue History
Date Modified	Username	Field	Change
2013-12-08 19:38	woife	New Issue
2013-12-09 10:30	andras	Note Added: 0000858
2013-12-09 10:30	andras	Status	new => resolved
2013-12-09 10:30	andras	Fixed in Version	=> 4.4
2013-12-09 10:30	andras	Resolution	open => fixed
2013-12-09 10:30	andras	Assigned To	=> andras

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