From sarahmanderni at gmail.com  Mon Mar  2 14:46:43 2015
From: sarahmanderni at gmail.com (sarah manderni)
Date: Mon, 2 Mar 2015 15:46:43 +0200
Subject: [Rd] R-devel does not update the C++ returned variables
In-Reply-To: <54F45105.40608@gmail.com>
References: <CAHyAz7TOELUyX2XW=8Abvuz2tU0_ZXVuyx-B84RBk7TQyM-mAA@mail.gmail.com>
	<54F45105.40608@gmail.com>
Message-ID: <CAHyAz7QvAyL-KgKp0B6pk=RDHAQs2LHeGS48HvATqZnbuoAfww@mail.gmail.com>

Thanks! I went through the online posts which supports the power of .Call
over .C. But my probably naive question is why does this work for my code
with R but not R-devel?
And another question is related to using .Call. Based on the manual page, I
do not need to change the function parameters when using .Call. So I can
run like this:
.Call("sppedUp", D, S, pD, pS, nrow(D), as.integer(N), length(N),
           ssq[i], i, as.integer(B), overlaps, overlaps.P)

But I am receiving the memory(?) related error:
terminate called after throwing an instance of 'std::bad_alloc'   what():
 std::bad_alloc
Now that I am running the code using .Call.

Thanks.

On Mon, Mar 2, 2015 at 2:01 PM, Duncan Murdoch <murdoch.duncan at gmail.com>
wrote:

> On 02/03/2015 3:50 AM, sarah manderni wrote:
> > Hi,
> >
> > Within my R code, I am using a C++ function as below:
> >
> >      overlaps <- matrix(0, nrow=B, ncol=length(N))
> >         overlaps.P <- matrix(0, nrow=B, ncol=length(N))
> >
> >        .C("speedUp", D, S, pD, pS, nrow(D), as.integer(N), length(N),
> >            ssq[i], i, as.integer(B), overlaps, overlaps.P, DUP=FALSE)
> >
> >
> > the function "speedUp", is supposed to update matrices overlaps and
> >  overlaps.P and it works with official R versions.
> > However, using the same code in R-devel, it does not update matrices and
> > they remain all zero without returning any errors.
>
> See the NEWS:  DUP=FALSE is now ignored.  It led to too many bugs.  Use
> the .Call interface if duplication causes problems.
>
> Duncan Murdoch
>
> > But, if I store the return values from C function in a variable lets say
> > "test" as follows:
> >
> > test <-        .C("speedUp", D, S, pD, pS, nrow(D), as.integer(N),
> > length(N),
> >            ssq[i], i, as.integer(B), overlaps, overlaps.P, DUP=FALSE)
> >
> > then the corresponding element of test to matrix "overlaps"
> > (test[["overlaps"]]) again has the updated values (correct non-zero
> values)
> > though the overlaps matrix itself is still empty.
> >
> > I mean in official R, the "overlaps" matrix is updated after calling the
> > function but not in R-devel. Also it works in both environment and return
> > correct values to variable "test" in R-devel as well.
> > Did you face any similar problem so that R-devel does not update the
> > variable returned by C++?
> >
> > Thanks for the help.
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>
>

	[[alternative HTML version deleted]]



[Rd] R-devel does not update the C++ returned variables
sarah manderni