[Rd] NAs produced by integer overflow (PR#10482)

[ripley at stats.ox.ac.uk]

What is the bug here?  You haven't told us what you think it is, and

> 110231L * 101347L
[1] NA
Warning message:
In 110231L * 101347L : NAs produced by integer overflow

is both intentional and documented: see ?Arithmetic.

Please do give a reproducible example (as we ask): yours is not as we 
have to guess the types of the objects (I can get similar results if I 
guess "integer", but not quite the same).

cur.obs <- 110231L
colfreq <- as.integer(c(14845,1222,4776,101347,2863))
names(colfreq) <- c("other","past","perfect","present","progressive")
sum(cur.obs)*(colfreq/sum(colfreq))
       other        past     perfect     present progressive
   13085.485    1077.162    4209.921   89334.771    2523.661
sum(cur.obs)*colfreq/sum(colfreq)
       other        past     perfect     present progressive
   13085.485    1077.162    4209.921          NA    2523.661
Warning message:
In sum(cur.obs) * colfreq : NAs produced by integer overflow

Note the fourth entry.


On Sat, 1 Dec 2007, stgries at gmail.com wrote:

> Full_Name: Stefan Th. Gries
> Version: R version 2.6.1 (2007-11-26)
> OS: Windows XP Home SP2
> Submission from: (NULL) (68.6.47.105)
>
>
> Hi
>
> A simple computation results in integer overflow:
>
> These are the relevant vectors:
>
>> sum(cur.obs)
> [1] 110231
>
>> colfreq
>      other        past     perfect     present progressive
>      14845        1222        4776      101347        2863
>
>> sum(colfreq)
> [1] 125053
>
> Now ...
>
> # this works ...
>> sum(cur.obs)*(colfreq/sum(colfreq)) # note: brackets around the division
>      other        past     perfect     present progressive
>  13085.485    1077.162    4209.921   89334.771    2523.661
>
> # and this doesn't ...
>> sum(cur.obs)*colfreq/sum(colfreq) # note: no brackets around the division
>      other        past     perfect     present progressive
>  13085.485    1077.162    4209.921                2523.661
> Warning message:
> In sum(cur.obs) * colfreq : NAs produced by integer overflow
>
>
>
> I saw this was reported for R 2.3.0 and 2.6.0 before, but I don't know whether
> it ever got dealt with. Here's my version information:

Please don't be vague: you need to give URLs for claims that something is 
'reported'.


> # -------------------------------------
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          6.1
> year           2007
> month          11
> day            26
> svn rev        43537
> language       R
> version.string R version 2.6.1 (2007-11-26)
> # -------------------------------------
>
> STG
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595