迭代求根

#include<stdio.h>#include<stdlib.h>#include<math.h>double getfunc ( int a, double n ){if (n == 0){           return 1;}return 0.5 * ( getfunc (a, n - 1 ) + a / getfunc (a, n - 1 ) );}int main(){int a;scanf ( "%d", &a );        double i = getfunc(a,10);printf ( "%.5lf", i );return 0;}