[Insight-developers] Limits of Histograms' FrequencyType

[Bradley Lowekamp]

The problem with creating a a double DenseFrequencyContainer is that  
the Histogram class with then have conflicting types for it's  
FrequencyType, one from the container the other from the Superclass,  
SampleType. This created problems with at least one virtual function.

Another possible solution would be just to improve the algorithm in  
ListSampleToHistogramGenerator so that if there is over 2^24 samples  
then it would chunk it up and use an iterative total histogram +  
accumulator histogram. This would only cause a small loss of precision  
but would give reasonable results. Perhaps this would also give an  
opportunity to parallelize this part too.

On Oct 21, 2008, at 2:50 PM, Bradley Lowekamp wrote:

> Hello,
>
> I am causing trouble with my large data sets again. I am seeing this  
> number a lot in my histograms: 1.67772e+07 which is 2^24 and the  
> limit of mantissa for 32-bit floats. Unfortunately, the frequency  
> container types don't take this as a template parameter. It seems  
> silly to create another container just for this purpose.
>
> Brad
>

========================================================
Bradley Lowekamp
Lockheed Martin Contractor for
Office of High Performance Computing and Communications
National Library of Medicine
blowekamp at mail.nih.gov


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