from random import random
from math import log10,log

def roundf(f):
    epsilon = 2.0**(log(f,2) - 51.0)
    return round(f + cmp(f,0)*epsilon,2)

def test_rounding():
    " Test the rounding function for up to 14 digits precision "
    fractions = [.015, .01499, .675, .67499]
    expecteds = ['.02', '.01', '.68', '.67']
    magnitudes = range(10)
    c = 0
    for mag in magnitudes:
        for i in xrange(len(fractions)):
            for x in xrange(10000):
                frac = fractions[i]
                exp = expecteds[i]
                n = int(random()*pow(10,mag)) + frac
                rounded = str(roundf(n))
                assert rounded.endswith(exp)

test_rounding()