#include<stdio.h> 
double seki(double x, double y); 
int main(void) 
{ 
 double (*p)(double x,double y) ; 
 double n1 = 2.0; 
 double n2 = 3.0; 
 p=seki ; 
 printf("%lf¥n", p(n1,n2)); 
 return 0; 
} 
double seki(double x, double y) 
{ 
 return x * y; 
}