Hello
I am new starting the library and I am having a probably very silly problem
using it. I modified the example program to do optimize the function
x[0]^2+x[1]^1 with the bound contraint -10<x[i]<10. when I use
the NLOPT_LD_MMA everything works fine, then when I try to use the DIRECT_L
algorithm in the following code:
#include <math.h>
#include <nlopt.h>
double myfunc(unsigned n, const double *x, double *grad, void *my_func_data)
{
/*if (grad) {
grad[0] = 2*x[0];
grad[1] = 2*x[1];
}*/
return x[1]*x[1]+x[0]*x[0];
}
int main(){
double lb[2] = { -10, -10 }; /* lower bounds */
double ub[2] = { 10, 10 }; /* lower bounds */
nlopt_opt opt;
//opt = nlopt_create(NLOPT_LD_MMA, 2); /* algorithm and dimensionality */
opt = nlopt_create(NLOPT_GN_DIRECT_L, 2); /* algorithm and dimensionality
*/
nlopt_set_lower_bounds(opt, lb);
nlopt_set_min_objective(opt, myfunc, NULL);
nlopt_set_xtol_rel(opt, 1e-4);
double x[2] = { 1.234, 5.678 }; /* some initial guess */
double minf; /* the minimum objective value, upon return */
int num=nlopt_optimize(opt, x, &minf);
if (num < 0) {
printf("nlopt failed %d!\n",num);
}
else {
printf("found minimum at f(%g,%g) = %0.10g\n", x[0], x[1], minf);
}
nlopt_destroy(opt);
return 0;
}
and I get:
nlopt failed -2!
Do you have any idea what I am doing wrong?
Thanks In advance!
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