Message-ID: <Pine.GSO.4.31.0103311950150.1231-100000@auk.stats>
Date: 2001-03-31T18:54:16Z
From: Brian Ripley
Subject: Is this a bug with a simple arithmetic operation with a vector object?
In-Reply-To: <005d01c0ba7c$eda505a0$23c4bfc8@jarnt>
On Sun, 1 Apr 2001, hzi wrote:
> Hello-
>
> While I was reading a tutorial book for R (actually, for S-Plus:Brian S. Everitt. A Handbook of Statistical Analysis using S-PLUS. Chapman & Hall, London, 1994) I tried to execute this simple exercise:
>
> > x <- -c(1,2,3,4,5,6)
> > X <- -c(10,11,12,100,-5,-6)
> >x+X
> [1] -11, -13, -15, -104, 0, 0
>
> As you can see, the added vectors resulted in negative numbers !
(the answer should have been: [1] 11, 13, 15, 104, 0, 0)
Why? Everitt's book is extremely badly typeset, and `< -' is in fact `<-'
not `<- -' as you have entered. But the laws of arithmetic say R was right.
> Mind you, this is R 1.2.1 for Windows, under WIndows ME, 64 Mb RAM, pIII 800 MHz. The same thing happens, however, with the recently distributed "R 1.2.2 patched".
Why `mind you'? A phrase involving `workmen' and `tools' springs to mind.
> Clues, anyone?
Find a more reliable (and less outdated) guide ....
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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