From jwe at bevo.che.wisc.edu  Tue Aug  5 11:47:50 2003
From: jwe at bevo.che.wisc.edu (John W. Eaton)
Date: Tue Aug  5 17:48:11 2003
Subject: [Rd] RE: [R] ^ operation much slower in R 1.7.1 than in R 1.7.0
	???
In-Reply-To: <x2smog2kzo.fsf@biostat.ku.dk>
References: <Pine.A41.4.44.0308050718200.240674-100000@homer01.u.washington.edu>
	<x2smog2kzo.fsf@biostat.ku.dk>
Message-ID: <16175.53670.329214.861007@devzero.bogus.domain>

On  5-Aug-2003, Peter Dalgaard BSA <p.dalgaard@biostat.ku.dk> wrote:

| Also, R is generally compiled with -D NO_MATH_INLINES because of some
| ancient messup with glibc. I'm not sure whether that is actually still
| necessary, but it is forcing the use of the non-inlined pow() function.

I think the origin of this option might be that someone reported a bug
in Octave because exp (-Inf) was returning NaN.  The problem turned
out to be that the inline version of exp returns NaN for Inf, NaN, and
-Inf arguments.  These days it seems that you don't get the inline
versions unless you use -ffast-math (at least that's what I just now
found with gcc 3.3).  Using -DNO_MATH_INLINES might still be needed
for some older GCC compiler/library combinations, so I don't think it
hurts.  I'm not sure whether it matters for R, but according to the
glibc math.h header the inline versions also don't set errno.

jwe


[Rd] RE: [R] ^ operation much slower in R 1.7.1 than in R 1.7.0 ???
John W. Eaton