From ihaka@stat.auckland.ac.nz  Tue Jan  6 23:51:15 1998
From: ihaka@stat.auckland.ac.nz (Ross Ihaka)
Date: Wed, 7 Jan 1998 12:51:15 +1300 (NZDT)
Subject: IEEE 754 Style Arithmetic
Message-ID: <199801062351.MAA09299@stat1.stat.auckland.ac.nz>

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
solid).

Q1:

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?

Q2:

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
problem?

	Ross
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IEEE 754 Style Arithmetic
Ross Ihaka