**Algorithm:**

This method can be derived from (but predates) Newton–Raphson method.

1 Start with an arbitrary positive start value x (the closer to the root, the better). 2 Initialize y = 1. 3. Do following until desired approximation is achieved. a) Get the next approximation for root using average of x and y b) Set y = n/x

**Implementation:**

/*Returns the square root of n. Note that the function */ float squareRoot(float n) { /*We are using n itself as initial approximation This can definitely be improved */ float x = n; float y = 1; float e = 0.000001; /* e decides the accuracy level*/ while(x - y > e) { x = (x + y)/2; y = n/x; } return x; } /* Driver program to test above function*/ int main() { int n = 50; printf ("Square root of %d is %f", n, squareRoot(n)); getchar(); }

**Example:**

n = 4 /*n itself is used for initial approximation*/ Initialize x = 4, y = 1 Next Approximation x = (x + y)/2 (= 2.500000), y = n/x (=1.600000) Next Approximation x = 2.050000, y = 1.951220 Next Approximation x = 2.000610, y = 1.999390 Next Approximation x = 2.000000, y = 2.000000 Terminate as (x - y) > e now.

If we are sure that n is a perfect square, then we can use following method. The method can go in infinite loop for non-perfect-square numbers. For example, for 3 the below while loop will never terminate.

/*Returns the square root of n. Note that the function will not work for numbers which are not perfect squares*/ unsigned int squareRoot(int n) { int x = n; int y = 1; while(x > y) { x = (x + y)/2; y = n/x; } return x; } /* Driver program to test above function*/ int main() { int n = 49; printf (" root of %d is %d", n, squareRoot(n)); getchar(); }

References;

http://en.wikipedia.org/wiki/Square_root

http://en.wikipedia.org/wiki/Babylonian_method#Babylonian_method

Asked by Snehal

Please write comments if you find any bug in the above program/algorithm, or if you want to share more information about Babylonian method.