Sophie Ancelet
2006-Jan-20 15:45 UTC
[Rd] Troubles with the function rmultinom.c of the R's Random Number Generator
Hi,
I'm simulating a Markov chain in Fortran interfaced with R-2.2.1 in order
to generate data according to a Markov Random Field called the Potts model.
R Version:
platform i686-pc-linux-gnu
arch i686
os linux-gnu
system i686, linux-gnu
status
major 2
minor 2.1
year 2005
month 12
day 20
svn rev 36812
Each loop of my Fortran calls the function rmultinom.c of the R's Random
Number Generator through the wrapper:
#include <R.h>
#include <Rmath.h>
void F77_SUB(sarmultinom)(int n,
double* prob,
int K,
int* rN){
rmultinom(n, prob, K, rN);}
My fortran program is:
subroutine testsarmultinom(n,prob,K,rN)
implicit none
integer n,K,rN(K)
double precision prob(K)
call rndstart()
call sarmultinom(n,prob,K,rN)
call rndend()
end
In order to understand better how the function rmultinom.c works, I have
written an R code which calls this fortran subroutine as follows:
system("R CMD SHLIB test-multinom.f wrapper.c")
dyn.load("~/Package/test/test-multinom.so")
n=1
prob=c(0.6,0.1,0.3)
K=3
rN=c(1,0,0)
res<- .Fortran("testsarmultinom",
as.integer(n),
as.double(prob),
as.integer(K),
as.integer(rN))
Unfortunately, I have some trouble with the results. First, this command
always returns 0 values. In other words, I always get:
>res[[4]]
[1] 0 0 0
Moreover, if I run this R code a second time, an error message appears:
Segmentation fault.
Has somebody ever used rmultinom.c and encountered these problems? My code
must be wrong but I don't know where. In this case, what is the correct way
to call the C function rmultinom.c?
Thanks in advance,
Sophie.
Sophie Ancelet
ENGREF
Laboratoire Grese
19 avenue du Maine
75 732 Paris Cedex 15
France
tel: 33 1 45 49 89 27
Prof Brian Ripley
2006-Jan-20 17:06 UTC
[Rd] Troubles with Fortran and C (was with the function rmultinom.c of the R's Random Number Generator)
All arguments to functions called from C by Fortran are pointers (or should be: yours are not). The error is within your own code. You don't want to call rndstart and rndend around every call, only before the first and after the last. This is not the list for advice om mixed Fortran/C programming, though. On Fri, 20 Jan 2006, Sophie Ancelet wrote:> > Hi, > > I'm simulating a Markov chain in Fortran interfaced with R-2.2.1 in order > to generate data according to a Markov Random Field called the Potts model. > > R Version: > platform i686-pc-linux-gnu > arch i686 > os linux-gnu > system i686, linux-gnu > status > major 2 > minor 2.1 > year 2005 > month 12 > day 20 > svn rev 36812 > > > > > Each loop of my Fortran calls the function rmultinom.c of the R's Random > Number Generator through the wrapper: > > #include <R.h> > #include <Rmath.h> > void F77_SUB(sarmultinom)(int n, > double* prob, > int K, > int* rN){ > rmultinom(n, prob, K, rN);} > > > > My fortran program is: > > subroutine testsarmultinom(n,prob,K,rN) > implicit none > integer n,K,rN(K) > double precision prob(K) > > call rndstart() > call sarmultinom(n,prob,K,rN) > call rndend() > end > > > In order to understand better how the function rmultinom.c works, I have > written an R code which calls this fortran subroutine as follows: > > system("R CMD SHLIB test-multinom.f wrapper.c") > dyn.load("~/Package/test/test-multinom.so") > > n=1 > prob=c(0.6,0.1,0.3) > K=3 > rN=c(1,0,0) > res<- .Fortran("testsarmultinom", > as.integer(n), > as.double(prob), > as.integer(K), > as.integer(rN)) > > > Unfortunately, I have some trouble with the results. First, this command > always returns 0 values. In other words, I always get: > >> res[[4]] > [1] 0 0 0 > > > Moreover, if I run this R code a second time, an error message appears: > Segmentation fault. > > Has somebody ever used rmultinom.c and encountered these problems? My code > must be wrong but I don't know where. In this case, what is the correct way > to call the C function rmultinom.c? > > Thanks in advance, > > Sophie. > > > > > Sophie Ancelet > ENGREF > Laboratoire Grese > 19 avenue du Maine > 75 732 Paris Cedex 15 > France > tel: 33 1 45 49 89 27 > > ______________________________________________ > 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
Sophie Ancelet
2006-Feb-06 09:50 UTC
[Rd] Troubles with Fortran and C (was with the function rmultinom.c of the R's Random Number Generator)
Thank you for the answer. However, I sought in Doc. Writing R extensions, in particular in the paragraph 5.6 "Calling C from FORTRAN and vice versa" (page 67) but I did not find anything which could help me to correct my code. Indeed, rmultinom.c is a particular function since arrays are passed in arguments. Has somebody ever written a wrapper for this function? Thanks in advance, Sophie. At 17:06 20/01/06 +0000, Prof Brian Ripley wrote:>All arguments to functions called from C by Fortran are pointers >(or should be: yours are not). The error is within your own code. > >You don't want to call rndstart and rndend around every call, only before >the first and after the last. > >This is not the list for advice om mixed Fortran/C programming, though.>On Fri, 20 Jan 2006, Sophie Ancelet wrote: > >> >> Hi, >> >> I'm simulating a Markov chain in Fortran interfaced with R-2.2.1 in order >> to generate data according to a Markov Random Field called the Potts model. >> >> R Version: >> platform i686-pc-linux-gnu >> arch i686 >> os linux-gnu >> system i686, linux-gnu >> status >> major 2 >> minor 2.1 >> year 2005 >> month 12 >> day 20 >> svn rev 36812 >> >> >> >> >> Each loop of my Fortran calls the function rmultinom.c of the R's Random >> Number Generator through the wrapper: >> >> #include <R.h> >> #include <Rmath.h> >> void F77_SUB(sarmultinom)(int n, >> double* prob, >> int K, >> int* rN){ >> rmultinom(n, prob, K, rN);} >> >> >> >> My fortran program is: >> >> subroutine testsarmultinom(n,prob,K,rN) >> implicit none >> integer n,K,rN(K) >> double precision prob(K) >> >> call rndstart() >> call sarmultinom(n,prob,K,rN) >> call rndend() >> end >> >> >> In order to understand better how the function rmultinom.c works, I have >> written an R code which calls this fortran subroutine as follows: >> >> system("R CMD SHLIB test-multinom.f wrapper.c") >> dyn.load("~/Package/test/test-multinom.so") >> >> n=1 >> prob=c(0.6,0.1,0.3) >> K=3 >> rN=c(1,0,0) >> res<- .Fortran("testsarmultinom", >> as.integer(n), >> as.double(prob), >> as.integer(K), >> as.integer(rN)) >> >> >> Unfortunately, I have some trouble with the results. First, this command >> always returns 0 values. In other words, I always get: >> >>> res[[4]] >> [1] 0 0 0 >> >> >> Moreover, if I run this R code a second time, an error message appears: >> Segmentation fault. >> >> Has somebody ever used rmultinom.c and encountered these problems? My code >> must be wrong but I don't know where. In this case, what is the correct way >> to call the C function rmultinom.c? >> >> Thanks in advance, >> >> Sophie.
Sophie Ancelet
2006-Feb-06 10:30 UTC
[Rd] Troubles with the function rmultinom.c of the R's Random Number Generator
Thank you for the answer. However, I sought in Doc. Writing R extensions, in particular in the paragraph 5.6 "Calling C from FORTRAN and vice versa" (page 67) but I did not find anything which could help me to correct my code. Indeed, rmultinom.c is a particular function since arrays are passed in arguments. Has somebody ever written a wrapper for this function? Thanks in advance, Sophie. At 17:06 20/01/06 +0000, Prof Brian Ripley wrote:>All arguments to functions called from C by Fortran are pointers >(or should be: yours are not). The error is within your own code. > >You don't want to call rndstart and rndend around every call, only before >the first and after the last. > >This is not the list for advice om mixed Fortran/C programming, though.>On Fri, 20 Jan 2006, Sophie Ancelet wrote: > >> >> Hi, >> >> I'm simulating a Markov chain in Fortran interfaced with R-2.2.1 in order >> to generate data according to a Markov Random Field called the Potts model. >> >> R Version: >> platform i686-pc-linux-gnu >> arch i686 >> os linux-gnu >> system i686, linux-gnu >> status >> major 2 >> minor 2.1 >> year 2005 >> month 12 >> day 20 >> svn rev 36812 >> >> >> >> >> Each loop of my Fortran calls the function rmultinom.c of the R's Random >> Number Generator through the wrapper: >> >> #include <R.h> >> #include <Rmath.h> >> void F77_SUB(sarmultinom)(int n, >> double* prob, >> int K, >> int* rN){ >> rmultinom(n, prob, K, rN);} >> >> >> >> My fortran program is: >> >> subroutine testsarmultinom(n,prob,K,rN) >> implicit none >> integer n,K,rN(K) >> double precision prob(K) >> >> call rndstart() >> call sarmultinom(n,prob,K,rN) >> call rndend() >> end >> >> >> In order to understand better how the function rmultinom.c works, I have >> written an R code which calls this fortran subroutine as follows: >> >> system("R CMD SHLIB test-multinom.f wrapper.c") >> dyn.load("~/Package/test/test-multinom.so") >> >> n=1 >> prob=c(0.6,0.1,0.3) >> K=3 >> rN=c(1,0,0) >> res<- .Fortran("testsarmultinom", >> as.integer(n), >> as.double(prob), >> as.integer(K), >> as.integer(rN)) >> >> >> Unfortunately, I have some trouble with the results. First, this command >> always returns 0 values. In other words, I always get: >> >>> res[[4]] >> [1] 0 0 0 >> >> >> Moreover, if I run this R code a second time, an error message appears: >> Segmentation fault. >> >> Has somebody ever used rmultinom.c and encountered these problems? My code >> must be wrong but I don't know where. In this case, what is the correct way >> to call the C function rmultinom.c? >> >> Thanks in advance, >> >> Sophie.