[C++]nlopt在vs2019配置后测试代码

#include<nlopt.h>
#include<nlopt.hpp>
typedef struct
{
       double a, b;
}my_constraint_data;
double myconstraint(unsigned n, const double *x, double *grad, void *data)
{
       my_constraint_data *d = (my_constraint_data *)data;
       double a = d->a, b = d->b;
       if (grad)
       {
              grad[0] = 3 * a*(a*x[0] + b)*(a*x[0] + b);
              grad[1] = -1.0;
       }
       return ((a*x[0] + b)*(a*x[0] + b)*(a*x[0] + b) - x[1]);
}
int count = 0;
double myfunc(unsigned n, const double *x, double *grad, void *my_func_data)
{
       ++count;
       if (grad)
       {
              grad[0] = 0.0;
              grad[1] = 0.5 / sqrt(x[1]);
       }
       return sqrt(x[1]);
}
int main()
{
       double lb[2] = { -HUGE_VAL, 0 };
       nlopt_opt opt;
       opt = nlopt_create(NLOPT_LD_MMA, 2);
       nlopt_set_lower_bounds(opt, lb);
       nlopt_set_min_objective(opt, myfunc, NULL);
       my_constraint_data data[2] = { { 2, 0 }, { -1, 1 } };
       nlopt_add_inequality_constraint(opt, myconstraint, &data[0], 1e-8);
       nlopt_add_inequality_constraint(opt, myconstraint, &data[1], 1e-8);
       nlopt_set_xtol_rel(opt, 1e-4);
       double x[2] = { 1.234, 5.678 };
       double minf;
       if (nlopt_optimize(opt, x, &minf) < 0)
       {
              printf("nlopt faild!\n");
       }
       else
       {
              printf("found minimum after %d evaluations\n",count);
              printf("found minimum at f(%g,%g)=&0.10g\n", x[0], x[1], minf);
       }
       nlopt_destroy(opt);
       system("pause");
       return 0;
}