python二分法计算平方根

#!/user/bin/python
# coding=utf-8

'''

'''


def sqrt(v,t = 0.0001):
    '''
        二分法计算平方根     
    '''
    v = v + 0.0
    s = 0
    e = v / 2
    r = 0
    while((e - s) > (t * 2)):
        r = (s + e) / 2
        if(r * r > v): 
            e = r
        elif (r * r < v):
            s = r
        else:
            return r 

    return r

print sqrt(9)
print sqrt(10,0.1)