C ++编译器错误：C3867使用函数作为类的成员时

Question

编译以下内容时：

#include "stdafx.h"
#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>

using namespace std;

#define A 10

double psi(double x);
double qgaus(double(*func)(double), double a, double b);
double normalize();

double psi(double x) {
    return pow(sin(M_PI_2*x/ A), 2);
}

double qgaus(double(*func)(double), double a, double b) {
    double xr, xm, dx, s;
    static double x[] = { 0.0, 0.1488743389, 0.4333953941, 0.6794095682,0.8650633666,0.9739065285 };
    static double w[] = { 0.0, 0.2955242247, 0.2692667193,  0.2190863625,0.1494513491,0.0666713443 };
    xm = 0.5*(b + a);
    xr = 0.5*(b - a);
    s = 0;
    for (int j = 1; j <= 5; j++) {
        dx = xr*x[j];
        s += w[j] * ((*func)(xm + dx) + (*func)(xm - dx));
    }
    return s *= xr;
}

double normalize() {
    double N;
    N = 1 / sqrt(qgaus(psi, 0.0, A));
        return N;
}

int main()
{
    double Norm = normalize();
    cout << Norm << endl;
    return 0;
}

此代码编译时没有错误。但是，当我尝试将两个例程放入一个类中时，如此处所示的更改。

class PsiC {
public:
    double psi(double x);
    double normalize();
};

double PsiC::normalize() {
    PsiC my_psi;
    double N;
    N = 1 / sqrt(qgaus(my_psi.psi, 0.0, A));                        
    return N;
}

现在在main中使用以下内容：

PsiC my_psi;
double Norm = my_psi.normalize();
cout << Norm << endl;

声明N = 1 / sqrt（qgaus（my_psi.psi，0.0，A））;给出编译错误：

'func': function call missing argument list; use '&func' to create a pointer to member.

注意：我现在只有两个成员;但是，我打算稍后再添加更多成员。