[Rd] Bug in dt() function in stats - accuracy only 6 dp.
m@echler @ending from @t@t@m@th@ethz@ch
Thu Jan 10 11:07:45 CET 2019
>>>>> mark chappell via R-devel
>>>>> on Wed, 9 Jan 2019 13:10:26 +1100 writes:
> Hi I believe the dt() function in stats has small areas of
> SmallRangeMostDetaileddf150.png shows this occurring in
> the 10-11th decimal place.
> MyD4 is computed using Myt_NC(), at the bottom of BugL.R -
> my function is very slow due to using mpfr, but i believe
> accurate to the accuracy of genhypergeo() which it uses -
> 14-15 dp.
> LargeRangeDiffdf150.png, which is difference between dt()
> and my function, shows spikes across -1.5 < x < 1.5.
> I assumed probably only a problem for large df, but
> SmallRangeCloseZerodf20.png, shows actually more of a
> problem with
> df = 20. Accuracy seems to be only to 6 decimal places.
We did not get a single piece of R code.
Maybe you've wanted to attach the 'BugL.R' R script mentioned
above, but failed to use 'text/plain' MIME encoding?
Note: If this is about using *non*central t-distribution (as the
above "NC" suggests), then this is *not* a bug per se,
as the help page *does* mention that the acuracy there is reduced.
Still, I have created an R bugzilla account for you to report
there, i.e., https://bugs.r-project.org/
> Using R version 3.5.2.
> [DELETED ATTACHMENT SmallRangeMostDetaileddf150.png, PNG image]
> [DELETED ATTACHMENT LargeRangeDiffdf150.png, PNG image]
> [DELETED ATTACHMENT SmallRangeCloseZerodf20.png, PNG image]
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