Square root program in C without using sqrt function [closed]

Question

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.

---

This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.

Closed 8 years ago.

Improve this question

I am trying to make a program in C to find the approximate square root of a number using the formula NG = 0.5( LG + N/ LG). So far i have:

#include <stdio.h> 
#include <math.h> 
int main(){
    double n;
    double LG=1;
    double NG;
    printf("Enter number");
    scanf_s("%lf",&n);
    do{
        NG=(.5*(LG+n/LG));
        LG=NG;
    }while((NG*NG-n)<.005);
    printf("The root is %lf",NG);
}

This structure works fine in java, but the loop doesn't seem to be executing in C.

Thanks for any advice.

Answer 1

You do not want to loop while NG*NG-n is less than .005. You want to loop while NG*NG is farther from n than desired.

The distance between NG*NG and n is fabs(NG*NG - n).