Hi, I have read R's Writing Extensions manual and am still confused about how to use some of the routines there when I call from C. Specifically, I am writing a little test function which I will optimize using the nmmin function which underlies R's optim() with Nelder-Mead. I guess I wonder what library/header files I should be using. I was using R_ext/Applic.h and linking with libR but I can not get it to work. (Btw, I am using RHEL4/FC4 Linux).
The function is very simple: all it does is calculate the sum of squared differences from a parameter, so the minimizer will be the mean. Actually, here is my code: #include<stdio.h> #include<stdlib.h> #include <R_ext/Applic.h> typedef struct { double *X; int n; } MyData; double myfunc(int m, double *par, void *ex) { MyData *mydata = ex; double *X = mydata->X; int n = mydata->n; double mu = par[0]; double sum = 0.0; int i; for (i=0; i<n; i++) { double t = X[i] - mu; sum += t*t; } return sum; } int main(void) { int i,n=1, trace=1, maxit=100, fail, fncount; double *par, abstol=0.0001, intol=.0001, alpha=1, beta=.5, gamma=2, *xin, *x, Fmin; MyData ex; par=malloc(n*sizeof(double)); xin=malloc(n*sizeof(double)); x=malloc(n*sizeof(double)); par[0]=5; xin[0]=5; ex.n=5; ex.X=malloc(ex.n*sizeof(double)); for(i=0;i<ex.n;i++) ex.X[i]=i; nmmin(n,xin,x,&Fmin,myfunc,&fail,abstol,intol,&ex,alpha, beta,gamma,trace,&fncount,maxit); free(par); free(x); free(xin); free(ex.X); return 0; } I compile using the following: gcc -o testex testex.c -std=c99 -Wall -pedantic -I/usr/lib/R/include -L/usr/lib/R/lib -lm -lR Which actually compiles without error, but I get Segmentation fault when I run it. Clearly, I am doing something wrong. Can someone please provide suggestions? Many thanks and best wishes, Aaarem ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html