On Mon, 9 May 2005, Zhijin Wu wrote:
Dear all, I am trying to use the C code for "integrate" function ( that calls Rdqagi and Rdqags) so that I can integrate a function defined in C, instead of passing from R. Is there a way for doing this?
My unsuccessful attempt: I looked into the files (including integrate.c, Applic.h) and 1. modified the definition of "integr_fn" by droping the environment "*ex", void integr_fn(double *x, int n) and dropped all use of "ex" used in the code
2. defined my checker function f1 and the vectorizing function "Cintfn" in place of "Rintfn"
double f1(double x){ return(x);} static void Cintfn(double *x, int n) { int i; for(i = 0; i < n; i++) x[i] = f1(x[i]); return; }
3. Similar to "call_dqags", I define a C function "my_call_dqags" that has it's own parameters of "lower, upper" and etc define in C, instead of parsing from R. And I call Rdqags(Cintfn, &lower, &upper, &epsabs, &epsrel, &result, &abserr, &neval, &ier, &limit, &lenw, &last, iwork, work); instead of Rdqags(Rintfn, (void*)&is, &lower, &upper, &epsabs, &epsrel, &result, &abserr, &neval, &ier, &limit, &lenw, &last, iwork, work);
I am not passing (void*)&is because I no longer have the "environment".
The code compiles fine with R CMD SHLIB. But it returns 5.3e-317 for my checker function f(x)=x, integration interval (1,2).
Thanks for any hint!
1) This is the wrong list: please read the posting guide.
2) You cannot just leave out arguments in C calls, so it seems that you need help with C programming rather than R. If you include the appropriate headers this will be checked, so I guess you have not.
-- Brian D. Ripley, [EMAIL PROTECTED] 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
______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
