[Rcppdevel] sugar: x+y and y+x gives different results when there are NA's in y
Søren Højsgaard
sorenh at math.aau.dk
Sat Nov 22 22:11:30 CET 2014
Thanks. May I suggest adding a remark about this in the sugarvignette (if it is not already there  in which case I apologize for not having seen it!)
Cheers
Søren
Original Message
From: Romain Francois [mailto:romain at renthusiasts.com]
Sent: 22. november 2014 14:36
To: Søren Højsgaard
Cc: rcppdevel at lists.rforge.rproject.org
Subject: Re: [Rcppdevel] sugar: x+y and y+x gives different results when
there are NA's in y

You get UB if the first is bigger than the second.

Envoyé de mon iPhone

> Le 22 nov. 2014 à 14:30, Søren Højsgaard <sorenh at math.aau.dk> a écrit :
>
> OK; thanks! Shall I read this such as "the behaviour is undefined"?
> Søren
>
> Original Message
> From: Romain Francois [mailto:romain at renthusiasts.com]
> Sent: 22. november 2014 13:25
> To: Søren Højsgaard
> Cc: rcppdevel at lists.rforge.rproject.org
> Subject: Re: [Rcppdevel] sugar: x+y and y+x gives different results
> when there are NA's in y
> 
> This has nothing to do with NA. It's just about the size difference.
> sugar does not make attempt at recycling. Your responsibility.
> 
> Romain
> 
> > Le 22 nov. 2014 à 11:48, Søren Højsgaard <sorenh at math.aau.dk> a
écrit :
> >
> > Dear all,
> > Came across this:
> >
> > #include <Rcpp.h>
> > using namespace Rcpp;
> >
> > //[[Rcpp::export]]
> > List sumxy(NumericVector x, NumericVector y){ NumericVector xy =
> > x+y; NumericVector yx = y+x; return List::create(xy, yx); }
> >
> > /*** R
> > x < c(1,3,5,7)
> > y < c(NA,2,4,6,8)
> > x+y
> > y+x
> > sumxy(x, y)
> > */
> >
> >> x < c(1,3,5,7)
> >> y < c(NA,2,4,6,8)
> >> x+y
> > [1] NA 5 9 13 9
> >> y+x
> > [1] NA 5 9 13 9
> >> sumxy(x, y)
> > [[1]]
> > [1] NA 5 9 13
> > [[2]]
> > [1] NA 5 9 13 8
> >
> > Is this intentional? Apologies if this has been documented
> > anywhere;
> was unable to find it.
> >
> > Regards
> > Søren
> >
> >
> > _______________________________________________
> > Rcppdevel mailing list
> > Rcppdevel at lists.rforge.rproject.org
> > https://lists.rforge.rproject.org/cgibin/mailman/listinfo/rcppd
> > eve
> > l
>
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