auto pb=p;这行的错误该如何修改？

#include<iostream>
    const double *f1(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f2(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f3(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
int main(void){
    using namespace std;
    double n=6;
    double *av=&n;
    const double *(*p[3])(double *ar,int n)={f1,f2,f3};
    const double *(*(*pp)[3])(double *ar,int n)=&p;
    auto pb=p;
    const double *(*pb[3])(double *ar,int n)={f1,f2,f3};    
    const double *ab=p[0](av,3);
    const double *ac=(*pb[1])(av,3);    
    return 0;
}

编译器显示如下错误：

如果删除了这行const double *(*pb[3])(double *ar,int n)={f1,f2,f3};又显示如下错误：

#include<iostream>
    const double *f1(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f2(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f3(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
int main(void){
    using namespace std;
    double n=6;
    double *av=&n;
    const double *(*p[3])(double *ar,int n)={f1,f2,f3};
    const double *(*(*pp)[3])(double *ar,int n)=&p;
    auto pb=p;              //这行编译器显示[Error] 'pb' does not name a type
    const double *ab=p[0](av,3);
    const double *ac=(*pb[1])(av,3);               //这行编译器显示[Error] 'pb' was not declared in this scope
    return 0;
}

[此贴子已经被作者于2020-11-25 11:48编辑过]

auto pb=p;删除掉这行后，可以正常运行。

#include<iostream>
    const double *f1(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f2(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
    const double *f3(double *ar,int n){
        double a=9;
        double *p=&a;
        return p;
    }
int main(void){
    using namespace std;
    double n=6;
    double *av=&n;
    const double *(*p[3])(double *ar,int n)={f1,f2,f3};
    const double *(*(*pp)[3])(double *ar,int n)=&p;
    const double *(*pb[3])(double *ar,int n)={f1,f2,f3};    
    const double *ab=p[0](av,3);
    const double *ac=(*pb[1])(av,3);    
    return 0;
}

但问题是这行const double *ac=(*pb[1])(av,3);为什么在这里可行？
(*pb[1])是指针pb[1]所指向的值，并不是指针本身，为何写成(*pb[1])?
应该改为const double *ac=pb[1](av,3);才对。