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Perfect number finder in python

In the interest of greater openness (sharing my inner life with the world and such), here is a bit of python I just wrote to find perfect numbers. After a few minutes of optimization, it is now quite fast and no longer brings OSX to its knees with memory-hungryness:

from math import *
def is_perfect(a):
	sum = 1 
	for i in xrange(2, floor(sqrt(a))):
		if a%i == 0:
			sum = sum + i + a/i
	if sqrt(a)%1 == 0: sum += sqrt(a)
	return sum == a

def find_perfect(limit):
	results = []
	for i in xrange(1, limit):
		j=2**i*(2**(i+1)-1)
		if is_perfect(j):
			results.append(j)

The Continuing Quest for Freedom from Telco Tirany

Rant

Why is Skype evil?

They choose to create their own proprietary network rather than interoperating with SIP, for the sole purpose of building a monopoly. Sure, it makes good business sense for them, since they are doubtless far more profitable than any public SIP service trying to compete in the same space. Can we blame them for wanting to make some dinero? No, I guess not. Will we fight them for control of the network? Duh of course!

Anyway, I've been using Skype for awhile since certain people I talk to also use it (there's the lock-in bit). Gizmo was pretty good, but not good enough (connection under bad conditions on public wifi etc was better under skype). Skype has its own cross-platform SIP client (using Trolltech's excellent dual-license QT library of course), which is free as in beer, but not Free Software. Anyway big woop. It also doesn't do video.

FF>> 6 months, and now the market is starting to shift around a bit. Wengo, a France-based SIP provider, has produced a very interesting SIP client:

  • Actually cross-platform (again via QT), unlike Skype which has a different and buggy version on each of Win, Lin and Mac.
  • Open source, and using open components (big woop), unlike Gizmo or Skype
  • Full-featured chat with all the major nets (MSN, AIM, Gtalk, IRC.....)
  • Video! Cross-platform video, fi-na-lly! Hallelujah!
  • Polished so it glistens. It's odd actually, the company clearly has enormously skilled and motivated engineers, but very poor marketing. They must have some other income source, perhaps in partnerships with Telcos.

The latest Wengophone release (2.1) claims to allow connections to other SIP providers. This is important because Wengo's service:

  1. is in French / France
  2. doesn't include important features like a US call-in number

So anyway I'm thinking that Sipphone's service might be the perfect match for Wengo's client. Testing follows, this article to document results.


Wikipedia does spoken articles

http://en.wikipedia.org/wiki/Category:Spoken_articles

I'm listening to the Lego article, it's a good format to listen to while doing something else, not too distracting but you pick up interesting snippets here and there.