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Old 2007-12-10, 18:25   #34
xilman
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Originally Posted by davieddy View Post
Is this helpful advice anything to do with me getting barred?
What's this about you being barred? I'm missing something...

Paul
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Old 2007-12-10, 18:38   #35
R.D. Silverman
 
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Originally Posted by xilman View Post
Bob, when I want your advice on when I should be helpful, I will ask for it. I trust you will be helpful when and if that occasion occurs.

In the meantime, please do me the courtesy of allowing me to make my own decisions on when, and when not, to be helpful. If you read my past history on this forum you will come across many examples of when my decision has gone each way.

Paul
Huh? None of my posts were directed towards any of your comments.
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Old 2007-12-10, 18:39   #36
R.D. Silverman
 
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Originally Posted by davieddy View Post
On the other hand, he might just enjoy the pleasure
of conversation.
In which case he should join a social club. This is not a social club.
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Old 2007-12-10, 18:53   #37
xilman
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Quote:
Originally Posted by R.D. Silverman View Post
Huh? None of my posts were directed towards any of your comments.
Review backwards in the thread where you will see:

Quote:
Originally Posted by me
Because they enjoy being helpful perhaps?
Quote:
Originally Posted by you
We should want to help those who are *** willing to learn ***.
We should not be doing other people's homework for them.
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Old 2007-12-10, 18:55   #38
davieddy
 
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Originally Posted by xilman View Post
Bob's advice was clearly aimed at the general case, not the specific instance exemplified by this thread.

As you have noted, on this particular occasion I was not helpful. Whether Bob noticed that or not remains to be seen.

(Actually, I did contribute to this thread, so you've not been paying attention. My contribution was to the effect that contributors may be helpful because they enjoy being helpful.)

Paul
I understood Bob's intitial advice.
And I took great notice of subsequent posts as a result.
I shall search for your contribution (which i vakue)'
On a local note, I also enjoy Flatlandrer's contrbutions
(Lunar Eclipses etc)

Love David
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Old 2007-12-10, 18:57   #39
davieddy
 
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Originally Posted by R.D. Silverman View Post
In which case he should join a social club. This is not a social club.
Perhaps it's an "Antisocial Club"
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Old 2007-12-11, 01:33   #40
davieddy
 
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Quote:
Originally Posted by xilman View Post
What's this about you being barred? I'm missing something...

Paul
Nothing much. Just another of Bob's throwaway suggestions
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Old 2007-12-11, 03:03   #41
davieddy
 
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I could have easily posted my query in the Homework Help
or Lounge forum, but elected this one because of the
"GIMPS" umbrella, to which the relevance is obvious.

Last fiddled with by davieddy on 2007-12-11 at 03:12 Reason: Grammer (sic);-)
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Old 2007-12-15, 15:24   #42
davieddy
 
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The kth bit represents 2kp+1.
I want to eliminate all multiples of a prime x (x<2p).
For what k (<x) is 2kp+1 a multiple of x?
Is there a clever way of answering(/programming) this?

David
Here's my idea of a succinct answer to a good question:

We seek a k for which 1=nx - k(2p) for some n.
We can do this because x and 2p are coprime (gcd=1).
We use the Extended Euclid algorithm to do this, and
needn't bother to find the corresponding n.

David

Last fiddled with by davieddy on 2007-12-15 at 15:35
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Old 2007-12-16, 10:16   #43
davieddy
 
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Quote:
Originally Posted by davieddy View Post
We seek a k for which 1=nx - k(2p) for some n.
We can do this because x and 2p are coprime (gcd=1).
As long as 2<x<p
Which might explain why my original (naive) program hanged when I
tried it (with a fixed range of x) for low (<=x) values of p
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Old 2007-12-16, 13:13   #44
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Huh?
Quote:
Originally Posted by davieddy View Post
2<x<p
Quote:
Originally Posted by davieddy View Post
(<=x) values of p
So p is greater than x, and it's also less than or equal to x?

Ah no, I see, everyone ignore this while I go bury my head in the sand again.

Last fiddled with by lavalamp on 2007-12-16 at 13:17
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