[Rd] Problem with R math library.
Dirk Eddelbuettel
edd at debian.org
Thu Jan 28 18:23:47 CET 2010
On 28 January 2010 at 17:59, Guillaume Yziquel wrote:
 Guillaume Yziquel a écrit :
 > Dirk Eddelbuettel a écrit :
 >>
 >> Salut Guilluame,
 >>
 >>  > val norm_rand : unit > float
 >>  > Random variates from the standard normal distribution. Bug:
 >> currently systematically returns 8.77332116900134373.
 >>   Any idea as to why the function systematically returns the same
 >> value?  Is there a way the math library should be initialised?
 >>
 >> I think it is pretty clearly documented in Rexts:
 >>
 >> However, before these are used, the user must call
 >> GetRNGstate();
 >> and after all the required variates have been generated, call
 >> PutRNGstate();
 >> These essentially read in (or create) `.Random.seed' and write it out
 >> after use.
 >
 > Fair enough. I admit I've been busy with low detail stuff, and omitted
 > to come back to Rexts.
 >
 > However, I have another question on which I do not find information (I
 > found it once, but do not know how to find it again...): What's the big
 > difference between using the R mathematical library in standalone mode
 > and not in standalone mode? How does it translate in terms of C
 > directives and linking modalities? I've noticed the MATHLIB_STANDALONE
 > macro, but I do not know how I should use it...
 >
 > All the best,

 OK. So concerning the headers:

 #define MATHLIB_STANDALONE
 #include <Rmath.h>

 Concerning dependencies: compile against only libRmath.so. Not against
 libR.so. (I wonder why this is so crucial, though...)
By design as libRmath is meanth to __standalone__ hence indepdent of R. This
is a a feature.
This is probably not what _you_ want as you are embedding R, so you need libR.
 Concerning documentation: Section 9 The standalone Rmath library from
 the Radmin.pdf documentation.

 This solved my problem, since I'm able to generated random values with
 norm_rand, unif_rand, etc...

 Thank you for your help.
Always a pleasure.
Dirk

Three out of two people have difficulties with fractions.
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