サブ関数間の相互呼び出し

        ：

double f1(int n, double a[], double x){}     1

double Get_Run_Time(double (*f)(int, double *, double)){    2
     (*f)(MAX, a, 1.1);
}

printf("Run time of f1: %.2e sec

", Get_Run_Time(f1));//main    

    printf("Run time of f1: %.2e sec

", Get_Run_Time(f1));//      f1
 
    printf("Run time of f2: %.2e sec
", Get_Run_Time(f2));//      f2

double f1(int n, double a[], double x)
{
    int i;
    double p = a[0];
    for(i = 1; i <= n; i++){
        p += a[i] * pow(x, i);
    }
    return p;
}
double f2(int n, double a[], double x)
{
    int i;
    double p = a[n];
    for(i = n; i > 0; i--){
        p = a[i - 1] + x * p;
    }
    return p;
}
double Get_Run_Time(double (*f)(int, double *, double))//          ，    ，           
{                                                    
    clock_t start, stop;
    int i;
 
    start = clock();
    for(i = 0; i < 100000; i++){
        (*f)(MAX, a, 1.1);
    }
    stop = clock();
    //printf("%f
%f
", (double)start, (double)stop);  // ：   clock_t  ，      double
    return (double)(stop - start) / CLOCKS_PER_SEC / 100000;  // CLOCKS_PER_SEC 1000
}