迭代算法求平方根

#include<stdio.h>#include<math.h>void main()
{
double a,x0,x1;    printf("input a:\n");    scanf("%lf",&a);    if(a<0)printf("ERROR!\n");    else
{
x0=a/2;
x1=(x0+a/x0)/2;        do
{
x0=x1;
x1=(x0+a/x0)/2;
}while(fabs(x0-x1)>=1e-6);
}    printf("Result:\n");    printf("sqrt(%g)=%g\n",a,x1);
}