Cooperative Agreement or Capitalist Takeover? You decide!

[Dubslow]

Originally Posted by LaurV

edit, in fact it makes no sense to include the whole text when you reply to the last post...(and it is not really polite, and not very cautious too, guys like me use to edit their last post many times, from English reasons, stupidity, tendency to boast, etc. hehe)

Yeah, I do that sometimes (a lot). If figure if somebody was going to die (or some other crazy bad thing) because of something they edited out, it wouldn't have been in there in the first place.

Originally Posted by axn

Ok. Some BotE calculations -- just to give you some perspective. A 12M digit number has appr 40M bits. On a 64-bit m/c, that is 625000 64-bit words. To multiply two such numbers by naive n^2 multiplication would take (625000^2 = 4e11) "64x64=128" multiplications. [You can halve that for squaring, but let's just go with this] A 2GHz m/c would need (2e9*200*60) clock cycles / 4e11 operations = 60 clock cycles / operation to be able to hit your mark. Typical modern processor can do a single "64x64=128" multiplication in under 10 clock cycles. So that leaves enough head room for the various other operations (like additions, memory writes, etc..) and still comfortably come in under your target. And this is the O(n^2) method.

Cool I think it's clear to everyone I pulled a large (relative to processors) amount of time straight out of my @$$ and didn't more than a half-an-ounce of thought into it

[davieddy]

Originally Posted by Dubslow

But bear in mind that squaring a large number is very hard.

Careful with that term when Silverman's around.
It's about as fatale as an after dinner mint.

(Pink Floyd and Cabaret)

D

[bloodIce]

Originally Posted by Dubslow

No, but PrimeNet is reporting false statements in the meantime, namely that "there are no factors below 2^62" is patently false.
http://mersenne.org/report_exponent/?exp_lo=2100451
I hope that BloodIce does create a Mersenne@Home and does report the factors.

I did register MersenneAtHome account (Mersenne@Home was not available) and I uploaded the two mentioned factors. The problem is that they went in as ECM assignments. However, the credit is so low, that it does not matter. Actually, my GPU produced both factors in less than 15 min. I agree that even if it the knowledge of the two factors does not matter for the discovery of future primes, it might save some TF, P-1 and ECM effort. By the way, I think I have spent half an hour or more GPU work on one of those exponents couple of months ago. Obviously that was total waste of time. In my opinion every factor found helps the big search, despite the fact that the ultimate proof for a number being composite is to find its factors.

[bloodIce]

Originally Posted by Prime95

I'm tempted to make BloodIce our official mers@home DB query manager :)

Flattering, but unnecessary . I shall help with whatever I can. By the way I can understand some polish, but that I am far from a constructive dialogue. I just want more factors in the GIMPS database and hopefully one day to see another Mprime. Let the human knowledge expand :-).

[davieddy]

But I hope it will entertain others (ignore if you feel like it).

I first got hooked on this stuff when Kim Novak came out of the
sea wearing nothing but a record breaking prime number circa Feb 2005.

David

[davieddy]

Pre-empt the Gerbils
See my latest in the Primenet forum (before they get there)

D

[davieddy]

Originally Posted by axn

Ok. Some BotE calculations -- just to give you some perspective. A 12M digit number has appr 40M bits. On a 64-bit m/c, that is 625000 64-bit words. To multiply two such numbers by naive n^2 multiplication would take (625000^2 = 4e11) "64x64=128" multiplications. [You can halve that for squaring, but let's just go with this] A 2GHz m/c would need (2e9*200*60) clock cycles / 4e11 operations = 60 clock cycles / operation to be able to hit your mark. Typical modern processor can do a single "64x64=128" multiplication in under 10 clock cycles. So that leaves enough head room for the various other operations (like additions, memory writes, etc..) and still comfortably come in under your target. And this is the O(n^2) method.

As a novice programmer, you may well find it very instructive/satisfying
to write a neat "school" long multiplication program.
I speak from experience.

D

Lesson 2: Division and square roots!

[davieddy]

Originally Posted by Dubslow

And do you think D or I could write even a basic FFT? (Actually, if I had my high school linear algebra text book I probably could, but it'd take me a few days at least.)

Go FORTH and multiply.

D

[Dubslow]

Originally Posted by davieddy

Go FORTH and multiply.

D

I can't take it at all. It's one of the large majority of cases where it's lost on me

Originally Posted by davieddy

As a novice programmer, you may well find it very instructive/satisfying
to write a neat "school" long multiplication program.
I speak from experience.

D

http://dubslow.tk/random/mersenne.txt

Originally Posted by davieddy

Lesson 2: Division and square roots!

Haven't done that yet. How does Newton's method compare to others for the sqrt? That's the only method that occurs to me off the top of my head.

[davieddy]

Originally Posted by Dubslow

I can't take it at all. It's one of the large majority of cases where it's lost on me

1) computer languages
2) The Holy Bible
3) Ernst

[Dubslow]

Originally Posted by davieddy

1) computer languages
2) The Holy Bible
3) Ernst

Ah, seems kind of obvious now.