- Jay Berg wrote:

> And I'm very puzzled as to what caused

Don't blame factor.exe.

> facter.exe to generate an extraneous factor, how it produced an

> actual real factor of a real factor of another (10^82+1) N

David Broadhurst has almost certainly solved the mystery. He suggests the

82-digit number must have been pasted twice to factor.exe, i.e. multiplied by

10^82+1.

Why didn't I think of that?

Probably because I'm not a nuclear physicist.

--

Jens Kruse Andersen - --- In primenumbers@yahoogroups.com, "Jens Kruse Andersen"

<jens.k.a@g...> wrote:> Jay Berg wrote:

suggests the

>

> > And I'm very puzzled as to what caused

> > facter.exe to generate an extraneous factor, how it produced an

> > actual real factor of a real factor of another (10^82+1) N

>

> Don't blame factor.exe.

> David Broadhurst has almost certainly solved the mystery. He

> 82-digit number must have been pasted twice to factor.exe, i.e.

multiplied by

> 10^82+1.

That solves it and allows me to recreate the results! Thanks for

helping resolve the problem.

I'd much rather it be my sloppy cut 'n pasting, than to be wondering

about a tool that has proven so valuable. Now that I know it was my

booboo, I can stop wondering.

Thanks again for helping to point out the error AND helping to

resolve the cause.

Jay - Is factor.exe open source?

Rob

-----Original Message-----

From: Jens Kruse Andersen [mailto:jens.k.a@...]

Sent: Friday, September 17, 2004 4:15 AM

To: primenumbers@yahoogroups.com

Subject: Re: [PrimeNumbers] Big ECM factor!

Jay Berg wrote:

> Anyway, sure enough, out popped a big factor.

Something went very wrong with your factor.exe.

> 3518005926601707472344309601987042658861560810593957361511478230105755

> 939320279041

> first trying brute force division by small primes

> PRIME FACTOR 101

> PRIME FACTOR 257

> PRIME FACTOR 641

> now trying 1000 iterations of brent's method

> PRIME FACTOR 68389

> PRIME FACTOR 114689

> PRIME FACTOR 274177

> PRIME FACTOR 65537

> PRIME FACTOR 974849

> PRIME FACTOR 2424833

> PRIME FACTOR 319489

> PRIME FACTOR 6700417

> PRIME FACTOR 26017793

> PRIME FACTOR 63766529

> PRIME FACTOR 6487031809

> now trying william's (p+1) method

> phase 1 - trying all primes less than 10000

> phase 2 - trying last prime less than 1000000

> PRIME FACTOR 190274191361

> PRIME FACTOR

> 1447745997018511893740076606031686237538345362413531560645573104006506

> 749609

The original number only had 82 digits and the product of the "prime

factors" is

far greater.

101, 68389 and the final 76-digit number are not factors.

They are actually the factors of 10^82+1.

The other numbers are all the factors of the original number.

--

Jens Kruse Andersen

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Yahoo! Groups Links - --- In primenumbers@yahoogroups.com, "Robert Sitton \(old\)"

<rsitton@a...> wrote:> Is factor.exe open source?

There's several versions of it floating around. I'd suggest you start

the search for a good source base at the following URL.

http://home.netcom.com/~jrhowell/math/software.htm

It's a very good tool for cracking most composites. Of course it

doesn't work on the "most desired". However it is very good on

breaking apart composite factors generated by other tools. - The "tool" in question is part of the Miracl big number library

(at least that is what the output text looks like). Miracl

can be downloaded from:

http://indigo.ie/~mscott

--- In primenumbers@yahoogroups.com, "Jay Berg" <jberg@e...> wrote:

> --- In primenumbers@yahoogroups.com, "Robert Sitton \(old\)"

> <rsitton@a...> wrote:

> > Is factor.exe open source?

>

> There's several versions of it floating around. I'd suggest you

start

> the search for a good source base at the following URL.

>

> http://home.netcom.com/~jrhowell/math/software.htm

>

> It's a very good tool for cracking most composites. Of course it

> doesn't work on the "most desired". However it is very good on

> breaking apart composite factors generated by other tools.