>From: Eric Hahn <[EMAIL PROTECTED]>
>To: "Nathan Russell" <[EMAIL PROTECTED]>
>CC: [EMAIL PROTECTED]
>Subject: Re: Mersenne: 65 bits (was Re: factoring)
>Date: Thu, 20 Apr 2000 16:12:12 -0700
>
>
>Nathan Russell wrote:
> >It will only get worse for the 486 users when PrimeNet begins
> >handing out exponents that will need factoring to 65 bits. Of
> >course, they can use factoroveride, but that's not helpful to
> >the network as a whole.
>
>However, the factoroverride switch is not designed for use with
>the PrimeNet server. For reasons unknown, the server does not
>release the exponent upon report of factoring being done when
>using the switch. That's why there was a complaint a while back
>on the list that somebody had several thousand factoring
>assignments out.
I had thought that the problem was only that Prime95 was trying to request
assignments, and then was unable to insert them in the worktodo file because
it was already at the maximum length.
>
> >For those who don't know, due to CPU design reasons that I
> >don't claim to understand, factoring to 65 bits takes easily
> >four or five times as long as factoring to 64 bits. In
> >version 19, it was set to take place for exponents 13.38M and
> >up. I believe PrimeNet will reach this point in a few months.
>
>While I had calculated it at 4.5 times as long (2x for the same
>percentage completion, and 2.25x for the iteration time), I've
>been getting ~4.2x as long. For some reason, IPS assigned me
>a couple dozen exponents just above 13.38M, and what would
>have normally taken me 38 hrs. for to 2^64, it's been taking
>~160 hrs. to do to 2^65...
Interesting. The figure I gave was an estimate based on my own experience
with the factoring I am now running for QA.
Nathan
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