Re: Mersenne: Re: M#40 verification run

2003-06-12 Thread Peter-Lawrence . Montgomery
Nathan Russell [EMAIL PROTECTED] comments --On Wednesday, June 11, 2003 10:58 PM -0400 George Woltman [EMAIL PROTECTED] wrote: 2) I'll change prime95 to NOT delete the save files when a new prime is found. When a prime is reported, I'll ask for the save file and rerun the last 30 minutes of

Re: Mersenne: Why is trial factoring of small exponents slower than large ones?

2003-02-06 Thread Peter-Lawrence . Montgomery
= From [EMAIL PROTECTED] Fri Feb 7 05:15:26 2003 = I am using mprime 22.12 on a pentium 166 MMX to do trial factoring. For the = exponents currently being assigned from primenet it takes this machine about = 12 minutes to factor from 2^57 to 2^58. = = I thought I would try factoring some small

Mersenne: Problem of the year(s)

2003-01-03 Thread Peter-Lawrence . Montgomery
A Mersenne number M_p = 2^p - 1, where p is prime and p 1000, has a prime divisor q with q == 1 (mod 2002) and q == -1 (mod 2001) [== denotes congruent]. Find q mod 2003. Peter Montgomery _ Unsubscribe list

Re: Mersenne: Request for help (especially ECM)

2002-11-10 Thread Peter-Lawrence . Montgomery
Brian J. Beesley [EMAIL PROTECTED] wrote - From [EMAIL PROTECTED] Sun Nov 10 20:22:33 2002 - On Saturday 09 November 2002 04:45, George Woltman wrote: - A harder problem is finding some smooth ECM curves to test. I do not - have tools to compute group orders. If someone can help by finding a

Re: Mersenne: Ernst Mayer's GIMPS pages

2002-11-08 Thread Peter-Lawrence . Montgomery
- From [EMAIL PROTECTED] Sat Nov 9 00:21:04 2002 Anurag Garg [EMAIL PROTECTED] writes - I have been unable to reach his pages using both the domain name - hogranch.com - which gets a non-existant domain name error - or the IP - address 209.133.33.182 . - - What gives? - Anurag - How many

Re: Mersenne: re: EE Times reports Faster Multiplication

2002-07-30 Thread Peter-Lawrence . Montgomery
Griffith, Shaun [EMAIL PROTECTED] asks Luke Welsh wrote: The EE times (www.eet.com) reports: Research by a team of U.K. mathematicians has produced a different approach to two of the most fundamental aspects of electronic computation: hardware addition and multiplication. Can

Re: Mersenne: Re: SF Bay GIMPS party (was Mersenne #39)

2001-11-18 Thread Peter-Lawrence . Montgomery
John R Pierce [EMAIL PROTECTED] writes - Can anyone come? Announce it on the list if you do it. - Where abouts are they held? - -- I will if I can. Depends on the date and family conflicts and where in the - rather sprawling SFBA it is... I'm in Santa Cruz, so naturally would prefer -

Re: Mersenne: Extracting digit of real number

2001-10-09 Thread Peter-Lawrence . Montgomery
To: [EMAIL PROTECTED] Subject: Mersenne: n-th decimal digit in real number Date: Tue, 09 Oct 2001 15:09:08 -0700 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: [EMAIL PROTECTED] X-OriginalArrivalTime: 09 Oct 2001 22:09:08.0593 (UTC) FILETIME=[048F1610:01C1510F] Sender:

Re: Mersenne: M727 factored!

2001-09-07 Thread Peter-Lawrence . Montgomery
Daran [EMAIL PROTECTED] asks Is M751 now the smallest unfactorised composite Mersenne? What is the smallest Mersenne not completely factorised? M751 and M809 are the first Mersennes with no known factor. The first holes in the 2^n - 1 table are 2,673- c151 and 2,683- c203. This

Re: Mersenne: M(2) - composite?!

2001-07-31 Thread Peter-Lawrence . Montgomery
From: Nathan Russell [EMAIL PROTECTED] Hi all, I'm a bit puzzled. The other day, I donated blood and kept my mind busy by doing LL tests on a few exponents mentally. I kept getting the result that the LL test for M(2) ends up resulting in a repeating value of -1, and certainly cannot

Re: Mersenne: Re: [PrimeNumbers] RSA

2001-07-30 Thread Peter-Lawrence . Montgomery
From: Nathan Russell [EMAIL PROTECTED] writes On Mon, 30 Jul 2001 11:45:26 -0700 (PDT), Pavlos S. [EMAIL PROTECTED] wrote: It has been a while since RSA labs published new factoring challenges..Does anyone know if there is any project going on at the moment for these challenges?

Re: Mersenne: P-1

2001-07-25 Thread Peter-Lawrence . Montgomery
From: CARLETON GARRISON [EMAIL PROTECTED] I honestly thought that the long term goal (maybe not by this panel but for others) was to factor all these numbers and that we were setting/recording a lower boundary for that effort. Carleton Garrison It will be a _long_ time before we

RE: Mersenne: Proth observations

2001-06-26 Thread Peter-Lawrence . Montgomery
Andy Hedges [EMAIL PROTECTED] asks: Anyone have any idea why for k = 659 there are very little primes? In fact for k up to 20 there are none (I haven't found any in this range yet!). Let k = 659. If n == 1 (mod 2) then k*2^n == 1 (mod 3) If n == 2 (mod 4) then k*2^n == 1 (mod 5) If n ==

Re: Mersenne: Re: Mersenne Digest V1 #843

2001-04-29 Thread Peter-Lawrence . Montgomery
Brian J. Beesley [EMAIL PROTECTED] wrote, in response to my earlier message The point of course is that there is a formal proof that, if a prime p is congruent to 3 modulo 4 and 2p+1 is also prime, then 2^p-1 is divisible by 2p+1 - which makes searching for a factor of M(p) by trying

Re: Mersenne: Re: Mersenne Digest V1 #843

2001-04-27 Thread Peter-Lawrence . Montgomery
On 26 Apr 2001, Brian J. Beasley wrote On 26 Apr 2001, at 6:34, Hans Riesel wrote: Hi everybody, If 2^p-1 is known to be composite with no factor known, then so is 2^(2^p-1)-1. Much as I hate to nitpick a far better mathematician than myself, this is seems to be an

Re: Mersenne: [slightly OT] Web discussion about distributed computing

2001-04-22 Thread Peter-Lawrence . Montgomery
Spike Jones [EMAIL PROTECTED] comments; --953E7B41754C35108B97B346 Nathan I liked your comment about the largest genuine composite: a number known to be composite but for which none of the factors are known. I suppose we could set up a computer to arbitrarily generate a few

Re: Mersenne: arithmetic progression of consecutive primes

2001-04-07 Thread Peter-Lawrence . Montgomery
From: [EMAIL PROTECTED] In a message dated 05/04/2001 05:19:38 GMT Daylight Time, "Gary Untermeyer" [EMAIL PROTECTED] writes: Let x be a prime number. Consider the series of numbers that take the following form: x, x + n, x + 2n, x + 3n, x + 4n, x + 5n, x + 6n, where n is

RE: Mersenne: LL question

2001-03-28 Thread Peter-Lawrence . Montgomery
- From: "Hoogendoorn, Sander" [EMAIL PROTECTED] - But what if the mod M comes out to 1 on one of - the intermediate steps? Then 1^2 - 2 = -1 - Then what? spike -Then you will be stuck in a loop, same thing happens when the outcome is - -2, -1, 0 and 2 This case never occurs. If M =

Re: Mersenne: Primitive roots for Galois transforms?

2001-03-13 Thread Peter-Lawrence . Montgomery
From [EMAIL PROTECTED] Tue Mar 13 16:06:33 2001 I wonder if there is possible to find primitive roots in GF(q^2), say a + ib, with the condition a^2 + b^2 = 1 mod q If this were possible, then (a + ib)*(a - ib) = 1 + 0i (mod q) i, e. the inverse of the root would be the

Re: Mersenne: Primitive roots for Galois transforms?

2001-03-11 Thread Peter-Lawrence . Montgomery
Jason Stratos Papadopoulos [EMAIL PROTECTED] writes Hello again. After working out how to do integer FFTs on the Alpha, I'm considering additional code that uses Fast Galois Transforms (FGTs), e.g. for complex integers in GF(p^2) for p a prime congruent to 3 mod 4. Bill Daly mentioned this

Re: Mersenne: Understanding the Propagate Carry Step in the LL Test

2001-01-05 Thread Peter-Lawrence . Montgomery
Fix a length n. If (a0, a1, ..., a_(n-1)) and (b0, b1, ..., b_(n-1)) are sequences of length n (in some ring or field), then their circular convolution is (c0, c1, ..., c_(n-1)) where c_i = sum_{i == j + k mod n} a_j * b_k For example, when n = 5, the circular convolution of (a0,

Re: Mersenne: 2000 - first calender year without a Mersenne

2000-12-31 Thread Peter-Lawrence . Montgomery
Nathan Russell observes: Well, unless there is an announcement within the next few hours, 2000 will be the first calender year in the history of GIMPS without a Mersenne prime. Is the number of searchers, and the power of their hardware, increasing enough to keep up with the

Re: Mersenne: n_th roots of 2 in a finite field?

2000-12-17 Thread Peter-Lawrence . Montgomery
If p is a prime which for which 2^22-th roots of unity exist, then p == 1 (mod 2^22). All such primes have 2 as a square, but 2 will be a 2^22 power only one time in 2^21. Of the 2^61/ln(2^61) primes between 2^61 and 2^62, only one in 2^42 will meet both requirements. You should find

Re: Mersenne: Factoring

2000-11-30 Thread Peter-Lawrence . Montgomery
Chris Nash proposed: We could let prime95 decide the next election grin. Give everybody a different prime number. Multiply the primes for candidate A together, likewise for B. And like in this election, unless we can completely factor the results, we wouldn't know who won, either.

Re: Mersenne: P4

2000-11-26 Thread Peter-Lawrence . Montgomery
Hi all, The mailing list has been quiet. I hope everyone enjoyed a happy Thanksgiving (or at least a good weekend for non-U.S. readers). The focus has been on double-checking, by a different mechanism than that which made the original count, alas in a non-Mersenne context.

Re: Mersenne: Likelihood Of Small Factors

2000-08-04 Thread Peter-Lawrence . Montgomery
If you are trying to factor Mp = 2^p - 1 where p is prime and p 2^58, then Mp can have no 59-bit factors [All factors are == 1 (mod 2*p).] But when factoring a random integer n, we estimate the probability of a factor between 2^51 and 2^59 as 1 - product (1 - 1/q)

Re: Mersenne: Another ECM question

2000-04-09 Thread Peter-Lawrence . Montgomery
Nathan Russell asks To start with, thanks to all those who answered my first question. What I want to know is as follows: If no factors are found for an exponent after running the needed curves for a 55 digit factor, what is done? Are additional curves run, or is that exponent put

Re: Mersenne: Another Conjecture?

2000-03-22 Thread Peter-Lawrence . Montgomery
"Nathan Russell" [EMAIL PROTECTED] Nathan Russell observes: This is something I've been toying with the last few days. I can prove that all even positive integers except 2, 4 and 8 can be written as the sum of Mersenne primes. All above 21 are either 0, 1 or 2 mod 3, and are therefore

Re: Mersenne: Fibonacci series..

1999-12-20 Thread Peter-Lawrence . Montgomery
"Ian L McLoughlin" [EMAIL PROTECTED] asks Since the list is quiet... Does a Fibonnacci series contain a finite or an infinite number of primes? From what I understand.. In a gen.F sequence if the first two numbers are divisible by a prime all its numbers are divisible by the same prime, if

Re: Mersenne: Mersennes are square free?

1999-11-24 Thread Peter-Lawrence . Montgomery
Daniel Grace [EMAIL PROTECTED] asks I looked at Chris Caldwells page on Wieferich (1909) primes but I could not see exaclty how p^2|2^(p-1)-1 relates to Mersennes with square factors? I can see that Mp=3(2^(p-1)-1). So my question is this "How does one derive Wieferich's result, from the

Re: Mersenne: Re: Mersenne Digest V1 #663; Norwegian Abel contest problem

1999-11-24 Thread Peter-Lawrence . Montgomery
[EMAIL PROTECTED] gives a UBASIC solution to Steinar's problem: First, perhaps I should explain some notation :-) a_11 is the letter `a', followed by 11 in subscript. x^2 is the letter `x', followed by the letter 2 in superscript (ie. `x^2' would be mathematically the same as `x*x').

Re: Mersenne: Modular arithemtic

1999-11-13 Thread Peter-Lawrence . Montgomery
Wojciech Florek [EMAIL PROTECTED] notes: Hi all! S.A. Fulling from Texas AM Univ. posted two articles at the Los Alamos Nat. Lab. archive. The first is on quantum computers and refers to the second one `abstracted' as "This is a pedagogical article cited in the foregoing research note"

Re: Mersenne: LL and Pollard-rho in one?

1999-10-28 Thread Peter-Lawrence . Montgomery
Alexander Kruppa [EMAIL PROTECTED] observes: Hi, the Lucas-Lehmer iteration L_0 = 4 L_{n+1} = L_n ^2 -2 looks suspiciously like an iteration used in Pollard-Rho: x_0 = a x_{n+1} = x_n ^2 +b Can this be used to do a LL test and Pollard-rho factoring attempt at once? I remember

Re: Mersenne: Smallest unfactored composite (was types of work to request...)

1999-10-16 Thread Peter-Lawrence . Montgomery
On Fri, Oct 15, 1999 at 01:03:57AM -0800, Gordon Bower wrote: Here's another argument - suppose the largest unfactored composite was C. How long did it take to determine the factorization (or primality) of C-2? (C-1 would be even.) Then to factor C would only take a marginally longer amount of

Re: Mersenne: targeting multiply/add (Was: K7 vs. x86)

1999-08-24 Thread Peter-Lawrence . Montgomery
Ernst Mayer writes: - Hi, Jason: - - Or, if you just want to cheapen a complex multiply, turn the standard - form - -xr,xi * yr,ri - xr*yr-xi*yi, xr*yi+xi*yr - - into - -xr,xi * yr,ri - xr*(yr - xi/xr * yi), xr*(yi + xi/xr * yr) - - and precompute xr and xi/xr. Presto! 2

Re: Mersenne: Simple question about P-1 factoring method

1999-08-17 Thread Peter-Lawrence . Montgomery
Will Edgingtom writes: If I understand P-1 factoring correctly, then using it to a stage one bound of k to try to factor M(p) will find all possible factors less than or equal to 2*k*p + 1. I'm assuming that p is less than k (or p is always used in the powering) and the convention several

Re: Mersenne: Worth it?

1999-07-21 Thread Peter-Lawrence . Montgomery
FAQ author Lucas Wiman [EMAIL PROTECTED] writes Well, this might not be a problem. If P-1 tries more than one base, all that is required (per Mn) is *one* gcd. We just multiply the remainders from the bases mod Mn, and then take the gcd on the final remainders. We could have the

Re: Mersenne: A slight divergence...

1999-07-19 Thread Peter-Lawrence . Montgomery
Chris Jefferson [EMAIL PROTECTED] writes It is well known that n is prime if for all prime factors of n-1, a^(n-1) = 1 mod n and a^((n-1)/q) is not 1 mod n. What are a and q? You want to say `if for each prime factor q of n-1, there exists a base a such that ...' . For example, take

Re: Mersenne: The $100,000 award for 10,000,000 digit prime

1999-07-18 Thread Peter-Lawrence . Montgomery
7) Anyone that makes a mathematical or algorithmic breakthrough that speeds up the search process. I'm talking about a doubling in search speed not a 1% speedup in assembly code. I think that this would be great -- but I seriously doubt that any improvement will be found. We can't get

Re: Mersenne: re: Mersenne prime exponent binary representations and 1's frequency (incl M38)

1999-07-12 Thread Peter-Lawrence . Montgomery
Ken Kriesel [EMAIL PROTECTED] writes: George asks, what about the bit second from the left? In total, 26 0 bits vs only 12 1 bits. (0 26 of 38 times or ~68.4%; 26/12=2.1...) Excluding p=2 and p= 3, to look only at interior bits, 25 0 bits vs only 11 1 bits; 0 25 of 36 times, ~69.4%;

Re: Mersenne: Why can't we...

1999-07-09 Thread Peter-Lawrence . Montgomery
Peter Foster asks: When doing an LL test we are always calculating the same series of numbers. The modulus is different, so we can't use the result of one test to help with another. I'm wondering why we don't do the following: Take 2 Mersenne numbers, m1 and m2 (m1 m2). Do the usual

Re: Mersenne: question

1999-07-06 Thread Peter-Lawrence . Montgomery
Jud McCranie [EMAIL PROTECTED] writes: At 10:47 AM 7/6/99 +0200, Benny.VanHoudt wrote: Now lets only focus on the set 2^p - 1 with p prime, i.e., the set of numbers that we are checking out at GIMPS. Has anyone proven that an infinite number these are NOT prime (this is VERY likely to be

Mersenne: Lehmer question

1999-07-04 Thread Peter-Lawrence . Montgomery
Problem A3 in Richard Guy's `Unsolved Problems in Number Theory' includes this question, by D.H. Lehmer: Let Mp = 2^p - 1 be a Mersenne prime, where p 2. Denote S[1] = 4 and S[k+1] = S[k]^2 - 2 for k = 1. Then S[p-2] == +- 2^((p+1)/2) mod Mp. Predict which

Re: Mersenne: Hmmm.

1999-07-01 Thread Peter-Lawrence . Montgomery
[EMAIL PROTECTED] writes Seeing as how anyone with even the most rudimentary of Internet searching skills (i.e. me) can find a publicly available Internet page with a certain highly important number on it, I ask why it is there. I thought that "those in the know" were *absolutely not*

Mersenne: SF Examiner story

1999-06-30 Thread Peter-Lawrence . Montgomery
Page A-12 of the June 30, 1999 San Francisco Examiner has a story `Math expert confirms a prime discovery' repeating the Oregonian story abut M38. The report does not give the precise exponent. The report mentions only George Woltman by name. Peter

Re: Mersenne: LL and factoring quitting

1999-06-14 Thread Peter-Lawrence . Montgomery
lrwiman [EMAIL PROTECTED] wrote: It has been mentioned several times recently that factoring is all integer work, and LL testing is nearly all floating point. It is my understanding that on intel CPU's, these are done on separate parts of the CPU. Would it increase net performance to do

Re: Mersenne: Repeating LL remainders

1999-05-18 Thread Peter-Lawrence . Montgomery
Chris Nash [EMAIL PROTECTED] wrote: Define L(n)=(2+sqrt(3))^n+(2-sqrt(3))^n. It turns out that what we usually call *the* Lucas sequence is just S(n)=L(2^n). Yes. We can check S(0) = L(1) = 4 and S(n+1) = S(n)^2 - 2 from the definitions. So S defines the familiar Lucas sequence.

Re: Mersenne: Back to the maths of primes for a sec....

1999-05-18 Thread Peter-Lawrence . Montgomery
"Nicolau C. Saldanha" [EMAIL PROTECTED] writes Do you have more precise information, or do you know where we can find it? (the help function inside maple gives only a very superficial explanation) Strong pseudoprime wrt which base? Probably not random, or the search for a counterexample

Re: Mersenne: P587 factored?

1999-05-09 Thread Peter-Lawrence . Montgomery
Observant "Foghorn Leghorn" [EMAIL PROTECTED] asks: I noticed that P587 is no longer on Geroge's ECM factoring page, but there is no factor listed. Did someone else find a factor? Robert Silverman sieved it by SNFS. CWI did the linear algebra. C(2,587+) 2769467 13119770765051463547

Re: Mersenne: LL-testing

1999-03-22 Thread Peter-Lawrence . Montgomery
"Benny.VanHoudt" [EMAIL PROTECTED] asks I was looking at the LL-test and thought of the following: To succeed a LL-test the final value (mod 2^p - 1) has to be zero. To be able to get this there has to be a number x (between 0 and 2^p - 2) such that x^2 = 2. This because in the final step of

Re: Mersenne: Completely Factored

1999-02-18 Thread Peter-Lawrence . Montgomery
"Sander Hoogendoorn" [EMAIL PROTECTED] asks Can sombody please tell me when a number is completely factored? The prime factors of 2^29 - 1 are 233, 1103, and 2089. The equation 2^29 - 1 = 233 * 1103 * 2089 gives the _factorization_ or _complete factorization_ of 2^29 - 1.

Re: Mersenne: Factoring

1999-02-15 Thread Peter-Lawrence . Montgomery
"Sander Hoogendoorn" [EMAIL PROTECTED] asks Last weekend when i was testing Prime 95 i noticed that factoring low numbers took much longer as high numbers. Factoring M17XXX from 2^52 to 2^54 took minutes per pass while factoring M9XX from 2^52 to 2^54 took about one minute to complete

Re: Mersenne: Questions on Crandall algorithm

1999-01-07 Thread Peter-Lawrence . Montgomery
Olivier Langlois comments (in response to others): First, let me thank you all for your helpful explanations. Is there someone that could be able to explain me the reasons that are behind the 2 conditions (q/N 32 and maximum convolution error is 0.5 for every Lucas-Lehmer

Re: Mersenne: Re: Mayer's Counter-Challenge

1998-12-04 Thread Peter-Lawrence . Montgomery
Dienst writes (in response to Ernst Mayer) If one instead does a fast polynomial-evaluation stage 2, even one with modest circular convolution length (to keep memory requirements reasonable), the stage 2 depth for a given amount of work should rise dramatically, perhaps 2-3 orders of

Re: Mersenne: How does this transform work

1998-11-05 Thread Peter-Lawrence . Montgomery
Can someone tell me the details of how the discreet weighted transform works, or tell me where to find information on this subject. It is described in an article by Crandall et al in Mathematics of Computation earlier this decade. We can use the FFT to multiply two

Re: Mersenne: A missunderstandment

1998-11-02 Thread Peter-Lawrence . Montgomery
Bojan Antonovic writes: (Somebody else wrote) Bah! 128 bit floats are quite useful. Think about percision. There are segments within the 64 bit range where you get terrible decmil precision. (such as with any large number) This becomes a problem with scaling large