[Rd] Bug in qbinom? (PR#511)
Thomas Lumley
thomas@biostat.washington.edu
Fri, 7 Apr 2000 08:33:13 -0700 (PDT)
On Fri, 7 Apr 2000 dtrenkler@nts6.oec.uni-osnabrueck.de wrote:
> n_10;p_0.5;jjx_0:n;qbinom(pbinom(jjx,n,p),n,p) # This one works as
> expected
>
> n_100;p_0.5;jjx_0:n;qbinom(pbinom(jjx,n,p),n,p) # This one causes
> severe problems
The problem is in qbinom(1-epsilon,100,0.5) for epsilon between 10^-15 and
10^-17. It appears to go for ever.
> pbinom(jjx,n,p)[89]-1
[1] -1.110223e-16
An even simpler version is
qbinom(1-1e-16,2,0.5)
Presumably a check for zero needs some fuzz.
-thomas
Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle
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