Write Your Own Square Root Function

Ever wondered how your calculator calculates the square root for a given number? It probably uses power series but an easier to grasp approach is the following:

Take a number t Let r be your guess of what the square root might be After that repeat the following a few times: r = (r+t/r)/2.0 r will now be a number pretty close to the square root of t

Below are two version of what this would look like in Python and C++. The initial guess is half the number t.

In Python:

def sqrt(t):
        r = t/2.0; t = float(t)
        i = 0
        while i < 10:
                r = (r+t/r)/2.0
                i += 1
        return r

In C++

long double sqrt(long double t) {
        long double r = t/2;
        for ( int i = 0; i < 10; i++ ) {
                r = (r+t/r)/2;
        }
        return r;
}

One Response to “Write Your Own Square Root Function”

Soki Says:

I have one work but i can’t write root square if can you help me

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