如何将成员函数传递给采用函数指针的合成成员？

Question

I have the below class that yields this error for the lines I commented: Description Invalid arguments 'Candidates are: Eigen::Matrix Forward_Euler(double ( )(double), double ( )(double), double (*)(double))' I'm getting confused when trying to search for a solution.

The signature for Forward Euler is:

Eigen::MatrixXd Forward_Euler(double (*f)(double), double (*gleft)(double), double (*gright)(double))

And my class is:

class C
{
protected:
    A x;
    B y;
    double a;
    double b;
    Eigen::MatrixXd u;

public:
    double f(double x)
    {
        return a;
    }
    double gleft(double tau)
    {
        return b
    }
    double gright(double tau)
    {
        return a*b;
    }
    FD_Euro_Put(): x(), y(), a(0), b(0){}
    FD_Euro_Put(char y1, double y2, double y3, double y4, double x2,
            double x3, double x4, double x5, double x6, double x7):
            x(x1, x2, x3, x4, x5, x6, x7)
    {
        double Xleft = x1*x2;
        double Xright = x1*x3;
        double Tauf = x1*x1;
        double NN = floor((x1/x2);
        a = x1*x2 - 0.5;
        b = x1*x2 + 0.5;

        pde = HeatPDE(y1, NN, Xleft, Xright, Tauf, Alpha); //begin problem area
        u.resize(pde.N+1, pde.M+1); 
        if(fdtype == 'f')
            u = pde.Forward_Euler(&f, &gleft, &gright);
        else if(fdtype == 'b')
            u = pde.Backward_Euler(&f, &gleft, &gright);
        else if(fdtype == 'c')
            u = pde.Crank_Nicolson(&f, &gleft, &gright); //end problem area
        else
            cout << "Incorrect choice for finite difference type!" << endl;
    }

Answer 1

Member function pointers and function pointers are not the same thing. Member function pointers have a much more difficult job and need to deal with things like virtual functions and the this pointer.

But look at the functions in your class! They are not really object functions because they use nothing from the object. You can either move them out of the class or make them static functions of the class. If you do either of those things you can use them as function pointers.

I think you have to use a class template and static functions. You can provide the arguments as template arguments.