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 2003-03-03, 14:18 #1 nukemyrman   Mar 2003 Yucaipa, CA, USA 10002 Posts How long does factoring run on 2^33,xxx,xxx type numbers? Hi, I'm running my first 2^33M-1 number and my machine has been factoring for 2 days now. It is a 2.5GHz, 1Gbyte DRAM machine. Does this sound reasonable? Thank you! Nick
 2003-03-03, 14:36 #2 QuintLeo     Oct 2002 Lost in the hills of Iowa 26×7 Posts It takes about a day for my P4 2.36 Ghz machine to factor a 20,xxx,xxx number - but those only factor to 2^67 depth. 33,xxx,xxx factor to 2^69 depth - so should take 4 days or a little less for your machine.
 2003-03-03, 14:45 #3 nukemyrman   Mar 2003 Yucaipa, CA, USA 23 Posts Thanx Q. I think it is great we're getting some good factoring in for the Number Theory guys and gals. Nuke
 2003-03-03, 15:44 #4 eepiccolo     Dec 2002 Frederick County, MD 2·5·37 Posts I recently factored a 2^333xxxxx-1 number to 2^68, and it took 42 hours running non stop with nothing else running on a P4 2.4Ghz. I think you would actually have to have an exponent greater than 3510000 to have Prime95 automatically trial factor to 2^69. I'm not sure, but I think the number I was working on had been previously TFed to 2^60.
2003-03-03, 16:16   #5
Prime95
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Aug 2002
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Re: How long does factoring run on 2^33,xxx,xxx type numbers

Quote:
 Originally Posted by nukemyrman I'm running my first 2^33M-1 number and my machine has been factoring for 2 days now. It is a 2.5GHz, 1Gbyte DRAM machine. Does this sound reasonable?
Trial factoring or P-1 factoring?

 2003-03-03, 17:31 #6 nukemyrman   Mar 2003 Yucaipa, CA, USA 23 Posts I don't mind running the factoring software a little longer than "Standard P95" is there soemhting I can put in the .int file to give it the OK to look a little further? Is how much time longer would I consume, for example, if I checked just one more bit. Also, would I lose the work I've done up 'till now.
 2003-03-03, 18:56 #7 smh     "Sander" Oct 2002 52.345322,5.52471 22458 Posts Factoring 1 bit deeper means you are factoring twice as far, so this takes at least double so long.
 2003-03-03, 19:08 #8 pakaran     Aug 2002 3×83 Posts And a lot longer than twice in the case of going past certain numbers of bits, 62 and more so 65 come to mind. Is the machine a P4 or an XP? The XP tends to factor pretty fast.
 2003-03-06, 10:42 #9 lycorn     "GIMFS" Sep 2002 Oeiras, Portugal 11×137 Posts nukemyrman wrote: I don't mind running the factoring software a little longer than "Standard P95"... Don´t use a P4 for that! P4s perform like crap on Trial Factoring, so stick to the minimum TF defined by the client, and use the power of the SSE2 instruction set for LL. From some data I have collected, I assure you it is a waste to engage P4s on long factoring assignments.
 2003-03-06, 13:29 #10 eepiccolo     Dec 2002 Frederick County, MD 2·5·37 Posts Trial Factoring over 2^64 I don't remember where I saw it, but I thought I saw somewhere that the P4 does really good with TFing once you get past 2^64, since than you have more than 64 bits. Is this true?
 2003-03-06, 13:35 #11 lycorn     "GIMFS" Sep 2002 Oeiras, Portugal 5E316 Posts Shortly after having posted my advice to nukemyrman, I realized we were in fact talking about TFing beyond 2^64. For those ranges, the SSE2 instructions are used, so I think P4s do indeed a lot better than up to 2^63. I don´t have figures for those ranges, but I will at least give P4s the benefit of doubt... :)

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