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The CWI suite produced a slightly smaller but denser matrix:
[QUOTE]Matrix has 4368656 rows and 4386633 columns. Remaining matrix weight is 326654668, density 0.0017%. Average prime weight 74.77, average relation-set weight 74.47. [/QUOTE] The BL was in progress, but I believe was expected to take about 6 weeks on Richard's 32-bit machine. Greg |
[QUOTE=jasonp;115339]I must say, this announcement has just made my evening. ...[/QUOTE]
Mine too! Even with the benefit of a heads-up from Richard; a real solid improvement in the matrix step (and filtering, even). Congratulations Greg and Jason. With the backlog cleared, we ought to be able to go on to finish the last of Bob's 768-bit list. Although, if I read the replies to King's poll correctly, Bob himself was voting in favor of harder Most Wanted base-2's. I gather that there was an intended follow-up poll; and append the candidates below. I'd like to see them all done; any order is good. More sieving contributors for NFSNET would move things along more quickly. Of course (as Greg has pointed out), someone to fill the missing Stat's position would also help. For that matter, no reason for NFSNET to monopolize these candidates, if someone else is interested in steping up ... -Bruce [QUOTE] You could start a new ballot ... Keep the options as 7,263- 6,284+ 2,787- 2,776+ 7,268+ [/QUOTE] Rest of the 768-bit list is 6,292+ 7,269- and 7,271- presumably for after the above ones from bases 6 and 7. The other Most wanted base-2's seem to be 2,779+ and 2,787+ with 2,776+ (above) More wanted. |
We have a winner!
[QUOTE=bdodson;115356] ...I gather that there was an intended
follow-up poll; and append the candidates [above] ... Rest of the 768-bit list is 6,292+ 7,269- and 7,271- presumably for after the above ones from bases 6 and 7. The other Most wanted base-2's seem to be 2,779+ and 2,787+ with 2,776+ (above) More wanted.[/QUOTE] That was quick; 6, 284+ wins. (Unless ECMNET gets a factor within the week.) Suppose 6,292+ would serve as a replacement for a poll. If that one wins next, the 768-bit list would be down to four last base-7's. -bd |
[QUOTE=bdodson;115356]Mine too! Even with the benefit of a heads-up from Richard; a
real solid improvement in the matrix step (and filtering, even). Congratulations Greg and Jason. With the backlog cleared, we ought to be able to go on to finish the last of Bob's 768-bit list. Although, if I read the replies to King's poll correctly, Bob himself was voting in favor of harder Most Wanted base-2's. [/QUOTE] The only reason for my preference was that I had promised Dick Lehmer that I would push to finish the base 2 tables that were incomplete from the 1st edition of the book. They have been around for a long time; the others are relative newcomers. Some time ago, NFSNET had asked for suggestions for some "easier" numbers. I had suggested the 768-bit list as an alternative to the harder base 2 numbers. In fact, if NFSNET wants to make a effort to finish the base 2 tables through 800 bits, I will put aside my work and help with the sieving. My siever is a good deal faster than the one used by NFSNET. There are two numbers left from 2- (one is supposedly "in progress", but I won't hold my breath), Three from the 2+, two from the 2,4K+ and 6 from the 2LM table (one of which will finish in about 2.5 days). |
[QUOTE=R.D. Silverman;115437]
There are two numbers left from 2- (one is supposedly "in progress", but I won't hold my breath), Three from the 2+, two from the 2,4K+ and 6 from the 2LM table (one of which will finish in about 2.5 days).[/QUOTE] Substantial progress since the last time we looked; finishing 2,1582L c162 will move 2,1598M C160 up into a fifth hole; with the 12 remaining all readily visible on Sam's page. Base-2's are fine with me; the only concern being that if there aren't enough sievers we'd drift up towards six months of sieving, which is a long time to wait for someone just considering joining. -bd |
[QUOTE=bdodson;115457]Substantial progress since the last time we looked; finishing 2,1582L c162
will move 2,1598M C160 up into a fifth hole; with the 12 remaining all readily visible on Sam's page. Base-2's are fine with me; the only concern being that if there aren't enough sievers we'd drift up towards six months of sieving, which is a long time to wait for someone just considering joining. -bd[/QUOTE] Here is 2,1582L. 2,1962M is filtering. 2,1630M is sieving. 2,1630M requires a quartic. It will be quite slow. 2,1582L c162 = p70.p92 p70 = 4785290367491952770979444950472742768748481440405231269246278905154317 p92 = 94732691570793956856759198414911779734119524415635396799864941098330965560269355785101434237 |
How do you use the additional factor p of an Aurifeuillian factor?
Taking out a factor p from x^p+1 involves the factorisation x^p+1 = (x+1)(x^{p-1}-x^{p+2}...\pm 1); the Aurifeuillian factors are from 4x^4+1=(2x^2+1)^2-(2x)^2 = (2x^2-2x+1) (2x^2+2x+1); but I don't see how those forms fit together so you can do both. What was the polynomial for 2,1582L or 2,1962M? |
Ah, I've figured this out.
Say x=28M+14. factor(2^14*x^28+1) is [code] [2*x^2 - 2*x + 1 1] [2*x^2 + 2*x + 1 1] [64*x^12 - 64*x^11 + 32*x^10 - 16*x^8 + 16*x^7 - 8*x^6 + 8*x^5 - 4*x^4 + 2*x^2 - 2*x + 1 1] [64*x^12 + 64*x^11 + 32*x^10 - 16*x^8 - 16*x^7 - 8*x^6 - 8*x^5 - 4*x^4 + 2*x^2 + 2*x + 1 1] [/code] now put u=2x+1/x; x^6*(u^6+2*u^5-10*u^4-20*u^3+16*u^2+32*u+8) is one factor and x^6*(u^6-2*u^5-10*u^4+20*u^3+16*u^2-32*u+8) the other. So it was just a matter of picking the right substitution, as I suppose SNFS polynomial generation always is. 12k+6 gives you a quartic [4 -4 2 -2 1] natively, or you can do the substitution to turn it into a quadratic and then change X and scale to get a sextic (which must be better than a quartic at >180 digits); 20k+10 gives you an octic which turns into a quartic and is annoying at >180 digits. Have I missed anything out? |
[QUOTE=fivemack;115756]How do you use the additional factor p of an Aurifeuillian factor?
Taking out a factor p from x^p+1 involves the factorisation x^p+1 = (x+1)(x^{p-1}-x^{p+2}...\pm 1); the Aurifeuillian factors are from 4x^4+1=(2x^2+1)^2-(2x)^2 = (2x^2-2x+1) (2x^2+2x+1); but I don't see how those forms fit together so you can do both. What was the polynomial for 2,1582L or 2,1962M?[/QUOTE] For 1582L: x^6 + 2x^5 - 10x^4 - 20x^3 + 16x^2 + 32x + 8 For 1962M: x^6 - 12x^4 + 4x^3 + 36x^2 - 24x - 8 |
[QUOTE=fivemack;115758]Ah, I've figured this out.
Say x=28M+14. factor(2^14*x^28+1) is [code] [2*x^2 - 2*x + 1 1] [2*x^2 + 2*x + 1 1] [64*x^12 - 64*x^11 + 32*x^10 - 16*x^8 + 16*x^7 - 8*x^6 + 8*x^5 - 4*x^4 + 2*x^2 - 2*x + 1 1] [64*x^12 + 64*x^11 + 32*x^10 - 16*x^8 - 16*x^7 - 8*x^6 - 8*x^5 - 4*x^4 + 2*x^2 + 2*x + 1 1] [/code] now put u=2x+1/x; x^6*(u^6+2*u^5-10*u^4-20*u^3+16*u^2+32*u+8) is one factor and x^6*(u^6-2*u^5-10*u^4+20*u^3+16*u^2-32*u+8) the other. So it was just a matter of picking the right substitution, as I suppose SNFS polynomial generation always is. 12k+6 gives you a quartic [4 -4 2 -2 1] natively, or you can do the substitution to turn it into a quadratic and then change X and scale to get a sextic (which must be better than a quartic at >180 digits); 20k+10 gives you an octic which turns into a quartic and is annoying at >180 digits. Have I missed anything out?[/QUOTE] You got it. |
[QUOTE=fivemack;115758]Ah, I've figured this out.
Say x=28M+14. factor(2^14*x^28+1) is [code] [2*x^2 - 2*x + 1 1] [2*x^2 + 2*x + 1 1] [64*x^12 - 64*x^11 + 32*x^10 - 16*x^8 + 16*x^7 - 8*x^6 + 8*x^5 - 4*x^4 + 2*x^2 - 2*x + 1 1] [64*x^12 + 64*x^11 + 32*x^10 - 16*x^8 - 16*x^7 - 8*x^6 - 8*x^5 - 4*x^4 + 2*x^2 + 2*x + 1 1] [/code] now put u=2x+1/x; x^6*(u^6+2*u^5-10*u^4-20*u^3+16*u^2+32*u+8) is one factor and x^6*(u^6-2*u^5-10*u^4+20*u^3+16*u^2-32*u+8) the other. So it was just a matter of picking the right substitution, as I suppose SNFS polynomial generation always is. 12k+6 gives you a quartic [4 -4 2 -2 1] natively, or you can do the substitution to turn it into a quadratic and then change X and scale to get a sextic (which must be better than a quartic at >180 digits); 20k+10 gives you an octic which turns into a quartic and is annoying at >180 digits. Have I missed anything out?[/QUOTE] I may have missed something. For example, for 2,1914M we get a quartic: [4,4,2,2,1] with root 2^159 . This becomes a quadratic x^2 + 2x - 2 with root 2^160 + 2^-159. To turn this into a sextic we make the substitution z^6 = x^2 giving z^6 + 2z^3 - 2, but the root is now z=(2^160 + 2^-159)^1/3. Computing a cube root mod N is as hard as factoring N itself. How do you suggest computing this cube root? |
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