使用boost ::绑定绑定成员函数，以提高::平分？ [英] Using boost::bind to bind member-function to boost::bisect?

问题描述

我已经与在此之前但现在它莫名其妙地工作。

现在，我下面的问题。我需要在我打电话的boost ::具有相同功能的平分到值绑定到成员函数。我发现pretty好教程，然后我跟着，但它似乎我还是做错了。

起初，我创建测试类在那里我得到了以下工作：

 的std ::对＆LT;双层，双＆GT;结果=平分（安培;函数功能，0.0，1.0，TerminationCondition（））;
            双根=（result.first + result.second）/ 2;
 

在我添加绑定对飞因为我认为它可以工作

 的std ::对＆LT;双层，双＆GT;结果=平分（提高::绑定（安培; CLASS ::功能，为此，_1），0.0，1.000000，TerminationCondition（））;
 

那结果是一个错误。错误：终止叫做抛出的一个实例后'的boost :: exception_detail :: clone_impl>是什么（）：错误函数boost ::数学::工具::平分：在boost ::数学::工具符号没有变化： ：平分，要么没有根找到，或有重根在区间（F（分钟）= -0.0032916729090909091）

反正这里是类::功能不作为成员函数出于某种原因，结合工作。我测试了它作为非成​​员和它的作品

  Double类::功能（双c）
{
/ *值：M_A，M_B，M_C，M_D和m_minus位于.h文件中* /正常规范;
双TEMP = * M_D的sqrt（C）;双总=（（1-的boost ::数学:: PDF（常态，（M_A * C + M_B）/温度）） - （1  -  M_C）+提振::数学:: PDF（常态，（M_A * C + M_B）/ TEMP））;收益率（总 -  m_minus）;
}
 

解决方案

如果我正确读取教程，它应该是：

 的std ::对＆LT;双层，双＆GT;结果=
    对分（提高::绑定（安培; CLASS ::功能，为此，_1，_2，_3）
        0.0，1.000000，TerminationCondition（））;
 

即。参数以的boost :: bind（）的是：

1. 函数（对象）的名称绑定到


2. 的参数传递给作为的功能的希望他们

有关你的情况，一个类:: memberFunc（），那将会是一种类* （可能这个但是任何类* 是确定）作为第一个，你从字面上国家本身，其次是参数之后传递到绑定的对象的

这些期货是由 _1 ， _2 等，这取决于它们的位置在调用时指定

例如：

 类addthree {
私人的：
    诠释秒;
上市：
    addthree（中间体term2nd = 0）：秒（term2nd）{}
    无效AddTo就（INT和放大器; term1st，const int的constval）{
        term1st + =（term2nd + constval）;
    }
}int类型的;
addthree AA;
提振::函数＆LT;无效（INT）＆GT; add_to_a =的boost ::绑定（安培; addthree :: AddTo就，＆安培; AA，A，_1）;
提振::函数＆LT;无效（无效）＆GT; inc_a =的boost ::绑定（安培; addthree :: AddTo就，＆安培; AA，A，1）;一个= 0; add_to_a（2）;性病::法院LT＆;＆LT; A＆LT;＆LT;的std :: ENDL;
一个= 10; add_to_a（一）;性病::法院LT＆;＆LT; A＆LT;＆LT;的std :: ENDL;
一个= 0; inc_a（）;性病::法院LT＆;＆LT; A＆LT;＆LT;的std :: ENDL;
[...]
 

I've had problems with this before but now it's somehow working.

Now I've following problem. I need to bind values into member-function before I call boost::bisect with the same function. I found pretty good tutorial and I've followed it but it seems that I'm still doing something wrong.

At first I created test class where I got following working:

std::pair<double, double> result = bisect(&Func, 0.0, 1.0, TerminationCondition());
            double root = (result.first + result.second) / 2;

After that I added binding "on the fly as I thought it could work"

 std::pair<double, double> result = bisect(boost::bind(&CLASS::Function,this, _1), 0.0, 1.000000, TerminationCondition());

Result of that was an error. error: terminate called after throwing an instance of 'boost::exception_detail::clone_impl >' what(): Error in function boost::math::tools::bisect: No change of sign in boost::math::tools::bisect, either there is no root to find, or there are multiple roots in the interval (f(min) = -0.0032916729090909091).

Anyway here is class::function which doesn't work as member function with binding for some reason. I tested it as non-member and it works

double CLASS::Function(double c)
{
/* values: m_a, m_b, m_c, m_d, and m_minus are located in .h file */

normal norm;
double temp = m_d*sqrt(c);

double total = ((1-boost::math::pdf(norm,(m_a*c+m_b)/temp))-(1 - m_c)+boost::math::pdf(norm,(m_a*c+m_b)/temp));

return (total - m_minus); 
}

解决方案

If I read the tutorial correctly, it should be:

std::pair<double, double> result =
    bisect(boost::bind(&CLASS::Function, this, _1, _2, _3),
        0.0, 1.000000, TerminationCondition());

I.e. the parameters to boost::bind() are:

1. The name of the function (object) to bind to
2. the arguments to pass to that, as the function expects them

For your case, a CLASS::memberFunc(), that'd be a CLASS * (possibly this but any CLASS * is ok) as the first, which you literally state as such, followed by the parameters later passed to the bound object.

These "futures" are designated by _1, _2 and so on, depending on their position at invocation time.

Example:

class addthree {
private:
    int second;
public:
    addthree(int term2nd = 0) : second(term2nd) {}
    void addto(int &term1st, const int constval) {
        term1st += (term2nd + constval);
    }
}

int a;
addthree aa;
boost::function<void(int)> add_to_a = boost::bind(&addthree::addto, &aa, a, _1);
boost::function<void(void)> inc_a = boost::bind(&addthree::addto, &aa, a, 1);

a = 0 ; add_to_a(2); std::cout << a << std::endl;
a = 10; add_to_a(a); std::cout << a << std::endl;
a = 0 ; inc_a(); std::cout << a << std::endl;
[ ... ]

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