void function_cx_1_func(const alglib::real_1d_array &c, const alglib::real_1d_array &x, double &func, void *ptr){
   func = c[0]+c[1]*x[0];
}

void function_cx_1_grad(const alglib::real_1d_array &c, const alglib::real_1d_array &x, double &func, alglib::real_1d_array &grad, void *ptr) {
   func = c[0]+c[1]*x[0];
   grad = "[0, 0]";
   grad[0] = 1;
   grad[1] = x[0];
}


int main(int argc, char **argv){

   alglib::real_2d_array x = "[[1], [2], [3], [4], [5]]";
   alglib::real_1d_array y = "[10, 15, 20, 25, 30]";
   alglib::real_1d_array c = "[1, 1]";;

   double epsf = 0;
    double epsx = 0.00001;
    alglib::ae_int_t maxits = 0;
    alglib::ae_int_t info;
    alglib::lsfitstate state;
    alglib::lsfitreport rep;

    //
    // Fitting without weights
    //
    alglib::lsfitcreatefg(x, y, c, true, state);
    alglib::lsfitsetcond(state, epsf, epsx, maxits);
    alglib::lsfitfit(state, function_cx_1_func, function_cx_1_grad);
    alglib::lsfitresults(state, info, c, rep);
   std::cout<<(int)info<<" "<<rep.rmserror<<" "<<c.tostring(1)<<std::endl;

   return 0;
}

grad = "[0, 0]";