Question

How would you prevent the errors when calling function biased_random defined below and what are the limits for arguments scale and bias to hold for preventing problems with big or small numbers?

def biased_random(scale, bias):
  return random.random() ** bias * scale

>>> sum(biased_random(1000, 10) for x in range(100)) / 100
64.94178302276364

>>> sum(biased_random(1000, 100000) for x in range(100)) / 100
0.0

>>> sum(biased_random(1000, 0.002) for x in range(100)) / 100
998.0704866851909

Answer 1

I’d use sys.maxint to figure out what the overflow point is. Then divide or nth-root it and compare with the number that you have:

r = random.random()
if sys.maxint ** (1.0/bias) < r:
    print "overflow imminent"
elif sys.maxint/float(scale) < r ** bias:
    print "overflow imminent"
else:
    print "overflow unlikely. To infinity, and beyond..."

Hope this helps