exhaustive enumeration demo

#quote from 'introduction to computation and programming using python, revised edition, MIT'            
def squareRootExhaustive(x, epsilon):
    """Assumes x and epsilon are positive floats & epsilon < 1
       Returns a y such that y*y is within epsilon of x"""
    step = epsilon**2
    ans = 0.0
    while abs(ans**2 - x) >= epsilon and ans*ans <= x:
        ans += step
    if ans*ans > x:
        raise ValueError
    return ans