[Tutor] Fwd: Help on finding the 1000th prime

[Shashwat Anand]

You'r trying naive algorithm. Finding prime is one of basic elements of
maths and programming. You may look at sieve of
eratosthenes<http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes>and
sieve
of atkin <http://en.wikipedia.org/wiki/Sieve_of_atkin>

On Tue, Nov 17, 2009 at 3:35 AM,
<christopher.henk at allisontransmission.com>wrote:

>
>
> Kent Johnson <kent37 at tds.net> wrote on 11/16/2009 04:00:02 PM:
>
>
> > ---------- Forwarded message ----------
> > From: Ray Holt <mrholtsr at sbcglobal.net>
> > Date: Mon, Nov 16, 2009 at 1:55 PM
> > Subject: RE: [Tutor] Help on finding the 1000th prime
> > To: Kent Johnson <kent37 at tds.net>
> >
> >
> > I hit the send button before I was ready. Here is the code that doesn't
> > work.
>        Not to nit pick, but try and copy the code exactly as you have it.
>  The code below has capitalization where it doesn't belong and indenting is
> not consistent, so there should be plenty of syntax errors if you tried to
> run it.  This makes it hard to figure out where your particular problem is.
>  Not sure if its a syntax problem or a algorithm problem.  Indentation is
> key in Python so without showing exactly what you have loops and branching
> is hard or impossible to follow.  This is also why it is good to include
> exactly what error you are experiencing.
>
> > primeCount = 0
> > primeCandidate = 2
>
>        You might find it easier to start with a different primeCandidate
> and handle 2 as a special case.
>
> > While primeCount <= 1000:
> > isPrime = True
> >        primeCandidate = primeCandidate + 2
>
>         primeCandidate is going to be 4,6,8,10,12,14,16,18,...
>         which won't yield many primes. see comment above
>
> >        for x in range(2, primeCandidate):
> >                if primeCandidate % x == 0:
> >        print primeCandidate, "equals", x, "*", primeCandidate/x
> >        isPrime = False
> > Print primeCandidate
> >        break
> > If isPrime:
> >        primeCount = primeCount + 2
> > Print primeCandidate
> >
>
>         It is hard to follow what is in which loop with the rest of the
> code, so I can't say much more on where you are having problems.  It looks
> like you have the parts there just a question of what goes where.
>
> Chris
>
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