Got it. I'll see if I can get it in. Thanks! On Wed, Oct 31, 2012 at 3:42 PM, David Mertens <[email protected]>wrote:
> I can work on some tests in a few days, though I'm busy at the moment. > > There should be two tests: one set that tests would be compare the > results of the factorial form and the Stirling form where they are in good > numerical agreement, basically for 50 < x < 100, and ensure that they agree > within bit noise (by one measure or another). > > The second set of tests are to ensure that the code for the combined form > (called pmf_poisson) gives results that are *identical* to those of the > factorial form for x < 50, and the Stirling form for x > 100. > > David > > > > On Wed, Oct 31, 2012 at 2:28 PM, Maggie X <[email protected]> wrote: > >> Thanks for the update, David! Would you mind adding a couple test cases? >> I'd be happy to add it too if you can suggest some numbers to test. >> >> Best, >> Maggie >> >> On Wed, Oct 31, 2012 at 12:38 PM, David Mertens <[email protected] >> > wrote: >> >>> Maggie (and other Stats PDLers) - >>> >>> I ran into some numerical stability issues with the Poisson probability >>> mass function. The Poisson distribution is mathematically well-behaved, but >>> is not numerically stable. Fortunately, I was able to use Stirling's >>> approximation to increase the range of accuracy and the allowed input range >>> to effectively work for anything. >>> >>> I've issued a pull request. You can check it out and comment here: >>> https://github.com/maggiexyz/PDL-Stats/pull/1 >>> >>> David >>> >>> P. S. Maggie's recent switch to Github didn't spur my interest in >>> PDL::Stats (blame my research for that), but it sure made it a heck of a >>> lot easier for me to manage this proposed modification. :-) >>> >>> -- >>> "Debugging is twice as hard as writing the code in the first place. >>> Therefore, if you write the code as cleverly as possible, you are, >>> by definition, not smart enough to debug it." -- Brian Kernighan >>> >>> >> > > > -- > "Debugging is twice as hard as writing the code in the first place. > Therefore, if you write the code as cleverly as possible, you are, > by definition, not smart enough to debug it." -- Brian Kernighan > >
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