[Edu-sig] Another idea of Conway

[Gregor Lingl]

Hi all,

on vacation in the Tyrolean Alps one evening
I've found the time to implement another (I assume
less well known) idea of John Conway.

Just for fun.

from fractions import Fraction

fracs = [Fraction(f) for f in
  "17/91 78/85 19/51 23/38 29/33 77/29 95/23 77/19 1/17 11/13 13/11 
15/14 15/2 55/1".split()]

def fracgame():
    z = Fraction(2,1)
    while True:
        for f in fracs:
            n = z * f
            if n.denominator == 1:
                break
        yield int(n)
        z = n

def pow2(z):
    n = 0
    while z % 2 == 0:
        n += 1
        z //= 2
    return (z == 1) * n
   
def what():
    fg = fracgame()
    while True:
        z = next(fg)
        n = pow2(z)
        if n != 0:
            yield n

what = what()
print(next(what))
print(next(what))

# the following will take 1 or 2 minutes

##w = 0 
##while w < 100:
##    w = next(what)
##    print(w)

Comments or discussion may follow when
I'm back to Vienna.

All the best,
Gregor