IEEE 754 Style Arithmetic
Wed, 7 Jan 1998 12:51:15 +1300 (NZDT)
I have been looking at the R mathematical library with a view to
making changes so that it will handle IEEE 754 entities like NaN and
+/- Inf. This appears to be not too hard and I am fairly well down
the path to converting the existing code (and simultaneously
converting some of the more suspect algorithms to something more
I have looked at the Splus implementation and I have a bit of a
problem with some of the decisions that have been made. For example
pnorm(0, 1, Inf) -> 0.5
This seems VERY dangerous to me. It's the kind of thing which could
make errors almost impossible to find. I would much rather that this
generated NaN (it's a domain error in my view).
There are some other nits like this too. Would it be a serious
problem if I were to "fix" these?
At present, the functions returning information about discrete
distributions work on integer (32-bit C int) arguments. This limits
the domain for these functions. Has anyone found that that this is a
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