On Jul 14, 2012, at 04:55 , Chandler Zuo wrote:
> Hi,
>
> Has anyone encountered the problem of rgamma function in C? The following
> simplified program always dies for me, and I wonder if anyone can tell me the
> reason.
>
> #include <Rmath.h>
> #include <time.h>
> #include <Rinternals.h>
>
> SEXP generateGamma ()
> {
> srand(time(NULL));
> return (rgamma(5000,1));
> }
>
> Has anyone encountered a similar problem before? Is there another way of
> generating Gamma random variable in C?
>
> P.S. I have no problem compiling and loading this function in R.
It doesn't even give off a warning??
The prototype in Rmath.h is
double rgamma(double, double);
and you should be returning an SEXP. As soon as something tries to interpret
the double value as a pointer -- Poof!
Notice that rgamma in C is not the same function as the R counterpart, in
particular it isn't vectorized, so only generates one random number at a time.
The long and the short of it is that you need to read up on sections 5.9 and
5.10 of Writing R Extensions.
>
> Thanks for suggestions in advance!
>
> --Chandler
>
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
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