Question

C语言用迭代法求平方根

读入被开方数a，用迭代法求出a的平方根。求平方根的迭代公式为：
X0=10
Xn=（Xn-1+a/Xn-1）/2 (n>0)
要求前后两次求出的X值的差的绝对值小于0.00001。

Answer 1

迭代公式都有了,直接套就好了阿..

int main()
{
double a=34;
double last = 0.0, curr = 10.0;

while(curr-last>0.00001 || last-curr>0.00001 ){
last = curr;
curr =(last+a/last)/2;
}

printf("%e\n", curr);
return 0;
}

Answer 2

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
int flag = 0;
cout<<"please enter a number:";
double a = 0.0;
cin>>a;
const double EPSTLON = 1E-14;
double xnew = a;
double xold = 0.0;
do{
xold = xnew;
xnew = (xold + a/xold)/2;
}while(fabs(xnew - xold) > EPSTLON);
cout<<"the square root is:"<<xnew<<endl;
cin>>flag;
return 0;
}

Answer 3

呵呵，我也是做到这题不会啊！大家共同努力！！