Poll & solutions

[elz]

First:

Poll #1689

Open to: Registered Users, detailed results viewable to: All, participants: 25

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Tickyboxes!

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Finished lecture 2
24 (96.0%)

Finished problem set 1
15 (60.0%)

Also, it occurs to me that it might be handy to have a place to post/discuss solutions to the problem sets, to see what we can learn from each other in the absence of TAs. If you actually go to MIT and the problem sets are still the same, don't read these. ;)

Fire away!

Comments

[elz]

And this one's for the second question:

from math import *
            
def primes_up_to_n(upper_limit):
    n = 3
    primes = [2]
    while n <= upper_limit:
        n_is_prime = True
        for prime in primes:
            n_is_prime = (n%prime != 0)
            if n_is_prime is False:
                break
        if n_is_prime:
            primes = primes + [n]
        n = n + 2
    return primes
    
def product_of_primes_to_n(n):
    primes = primes_up_to_n(n)
    sum_of_logs = 0
    for prime in primes:
        sum_of_logs += log(prime)
    print "The sum of the logs of the primes, the number n, and the ratio of these two quantities are:"
    print "%f, %i, %f" % (sum_of_logs, n, sum_of_logs/n)    


n = int(raw_input('Give me an n:\n'))
product_of_primes_to_n(n)

It would be more efficient if I smushed them together, but I wanted to see if the first function would work. For, you know, all the times I need lists of prime numbers in my daily life. *g* I'm not totally sure why the ratio is significant, but it does get closer to 1.

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[(Anonymous)]

As much as I like the EF 35mm f/2, I would have taken a cheaper EF-S f/1.8 if there was one like in Nikonland.As oehtrs have said, a refresh of the f/2 wouldn't hurt. The first time I heard the AFD going on that I thought the world was ending.I also wonder if there is room to move to a three tier prime at 35mm like at 50mm? That is a dirt cheap one (EF-S f/1.8), a regular one (EF f/2 refresh), and an expensive one (f/1.4).