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From "Ole Ersoy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MATH-519) GaussianFitter Unexpectedly Throws NotStrictlyPositiveException
Date Sat, 19 Feb 2011 23:53:38 GMT

    [ https://issues.apache.org/jira/browse/MATH-519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12996933#comment-12996933
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Ole Ersoy commented on MATH-519:
--------------------------------

I like the last option the best.  I'm wondering though whether we are placing constraints
on variables that are not supposed to be constrained?

Perhaps the optimizer should be allowed to call a method on Gaussian that does not effectively
constrain the valid values of sigma?



> GaussianFitter Unexpectedly Throws NotStrictlyPositiveException
> ---------------------------------------------------------------
>
>                 Key: MATH-519
>                 URL: https://issues.apache.org/jira/browse/MATH-519
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.0
>            Reporter: Ole Ersoy
>             Fix For: 3.0
>
>         Attachments: GaussianFitter.java, GaussianFitter2Test.java
>
>   Original Estimate: 4h
>  Remaining Estimate: 4h
>
> Running the following:
>     	double[] observations = 
>     	{ 
>     			1.1143831578403364E-29, 
>     			 4.95281403484594E-28, 
>     			 1.1171347211930288E-26, 
>     			 1.7044813962636277E-25, 
>     			 1.9784716574832164E-24, 
>     			 1.8630236407866774E-23, 
>     			 1.4820532905097742E-22, 
>     			 1.0241963854632831E-21, 
>     			 6.275077366673128E-21, 
>     			 3.461808994532493E-20, 
>     			 1.7407124684715706E-19, 
>     			 8.056687953553974E-19, 
>     			 3.460193945992071E-18, 
>     			 1.3883326374011525E-17, 
>     			 5.233894983671116E-17, 
>     			 1.8630791465263745E-16, 
>     			 6.288759227922111E-16, 
>     			 2.0204433920597856E-15, 
>     			 6.198768938576155E-15, 
>     			 1.821419346860626E-14, 
>     			 5.139176445538471E-14, 
>     			 1.3956427429045787E-13, 
>     			 3.655705706448139E-13, 
>     			 9.253753324779779E-13, 
>     			 2.267636001476696E-12, 
>     			 5.3880460095836855E-12, 
>     			 1.2431632654852931E-11 
>     	};
>   
>     	GaussianFitter g = 
>     		new GaussianFitter(new LevenbergMarquardtOptimizer());
>     	
>     	for (int index = 0; index < 27; index++)
>     	{
>     		g.addObservedPoint(index, observations[index]);
>     	}
>        	g.fit();
> Results in:
> org.apache.commons.math.exception.NotStrictlyPositiveException: -1.277 is smaller than,
or equal to, the minimum (0)
> 	at org.apache.commons.math.analysis.function.Gaussian$Parametric.validateParameters(Gaussian.java:184)
> 	at org.apache.commons.math.analysis.function.Gaussian$Parametric.value(Gaussian.java:129)
> I'm guessing the initial guess for sigma is off.  

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