对于算法boost-brent_minima.
当函子没有构造函数时,示例代码工作正常：

#include <boost/math/tools/minima.hpp>

struct funcdouble
{
  double operator()(double const& x)
  { //
    return (x + 3) * (x - 1) * (x - 1); // (x + 3)(x - 1)^2
  }
};

int bits = std::numeric_limits<double>::digits;

std::pair<double,double> r = brent_find_minima(funcdouble(),-4.,4. / 3,bits);

std::cout.precision(std::numeric_limits<double>::digits10);
std::cout << "x at minimum = " << r.first << ",f(" << r.first << ") = " << r.second << std::endl;

但是,当我使用构造函数生成这样的自定义函子时：

struct solver_test{

    solver_test::solver_test(std::string expression_string,std::string x_name_) : x_name(x_name_){
        symbol_table.add_constants();       
        symbol_table.create_variable(x_name);
        expression.register_symbol_table(symbol_table);     
        parser.compile(expression_string,expression);
    };

    double operator()(double x) {
        symbol_table.get_variable(x_name)->ref() = x;
        double value = expression.value();
        return value;
    };

    std::string x_name;
    exprtk::symbol_table<double> symbol_table;
    exprtk::expression<double> expression;
    exprtk::parser<double> parser;

};

int bits = std::numeric_limits<double>::digits;

solver_test test_root_finder("(x + 3)(x - 1)^2","x");
std::pair<double,double> r = boost::math::tools::brent_find_minima(test_root_finder,f(" << r.first << ") = " << r.second << std::endl;

我得到编译器错误C2280 – 使用brent_find_minima在行上引用已删除的函数.尝试时也会发生此错误：

std::pair<double,double> r = boost::math::tools::brent_find_minima(solver_test("(x + 3)(x - 1)^2","x"),bits);

如何在没有事先实例化的情况下传递带有构造函数的仿函数？

如果我看看以前的帖子

How do C++ functor constructors get called when used with for_each or std::transform

提供的答案似乎不适用于这种情况.