sqr_root.py

#!usr/bin/python3

def main():
    '''Return the square root of an positive integer that has no integer square root'''
    # Return middle value between two numvers
    def get_middle(lower, greater):
        return ((greater-lower)/2) + lower

    value = int(input())

    # Lower interval value
    lower = 0
    # Greater interval value
    greater = value

    # Result precision
    precision = 0.0001

    # Middle value of the current interval
    middle = get_middle(lower, greater)

    # Loop while interval is greater than precision
    while (greater-lower) > precision:
        if (middle*middle) > value:
            greater = middle
        else:
            lower = middle

        # Set new middle
        middle = get_middle(lower, greater)

    # Print result
    print(str(value) + ": " + ('%.3f' % middle))

main()