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Forum: Factoring 2009-12-22, 05:09
Replies: 27
Views: 1,177
Posted By nfortino
What happens if you use -m{arch,tune}=native? ...

What happens if you use -m{arch,tune}=native?

I convenient to use native without all the manual editing of makefiles, with no performance impact (I think this is new with gcc 4.3).
Forum: Msieve 2009-12-13, 06:50
Replies: 223
Views: 21,131
Posted By nfortino
SourceForge has always made that hard to find (in...

SourceForge has always made that hard to find (in the current incarnation, it's the develop tab). You'll need an svn client, and then it's the equivalent of:

svn co...
Forum: Puzzles 2009-11-09, 17:15
Replies: 34
Views: 1,121
Posted By nfortino
Retina's code is almost exactly what gcc does...

Retina's code is almost exactly what gcc does (assuming it uses the fp registers, and not the xmm registers) under -O3, with the default control word of 0x37f. Have a look at the output of...
Forum: Puzzles 2009-11-08, 08:09
Replies: 34
Views: 1,121
Posted By nfortino
I think it is actually legal to loop forever (in...

I think it is actually legal to loop forever (in c, representation must be IEEE compliant, but accuracy of operations and many compile-time optimizations are mostly implementation defined). I think...
Forum: Software 2009-11-08, 08:01
Replies: 180
Views: 38,175
Posted By nfortino
Other than violating the principle of least...

Other than violating the principle of least surprise, it's not wrong. cpuid has always returned the maximum APIC address, which in the new x2APIC scheme is no longer the same as core count and thread...
Forum: Puzzles 2009-11-07, 22:37
Replies: 34
Views: 1,121
Posted By nfortino
Actually, gcc (and the c standard) is rather...

Actually, gcc (and the c standard) is rather clear about not respecting exact rounding behavior. The issue is not precision, but rather associativity and contraction (-fassociative-math,...
Forum: Puzzles 2009-11-07, 05:36
Replies: 34
Views: 1,121
Posted By nfortino
Great puzzle! Interesting indeed. On...

Great puzzle!



Interesting indeed. On my 64 bit machine, gcc uses the xmm registers regardless of optimization flags, giving 49. Compiling with -m32 reproduces your results.

Looking at the...
Forum: Puzzles 2008-04-30, 08:00
Replies: 20
Views: 908
Posted By nfortino
Personally, I wouldn't bother with the bit array...

Personally, I wouldn't bother with the bit array at all, but rather just stop checking once a number smaller than I started with is reached. If you start at 3 and go up, you are assured to be correct...
Forum: Puzzles 2006-05-09, 00:52
Replies: 29
Views: 1,835
Posted By nfortino
In addition to being the smallest integer which...

In addition to being the smallest integer which can be written as the sum of a pair of cubes in two different ways, 1729 is also the third Carmichael number. Various tellings of the story have...
Forum: Puzzles 2006-01-09, 04:30
Replies: 28
Views: 1,819
Posted By nfortino
Actually, the Sun's tidal forces are about a...

Actually, the Sun's tidal forces are about a third of that of the Moon, and thus contribute significantly to the tides. The interaction between the tides caused by the Sun and the tides caused by the...
Forum: Lounge 2005-07-17, 03:14
Replies: 93
Views: 6,847
Posted By nfortino
Try looking at N37 44 42 E107 28 30, just SW of a...

Try looking at N37 44 42 E107 28 30, just SW of a 2X3 km lake. The wall (the white line interrupted by darker towers) can be followed almost 100 km running NW. It can be seen at an altitude of 150 km...
Forum: Puzzles 2005-06-21, 20:15
Replies: 44
Views: 1,224
Posted By nfortino
A 3: Find a fraction which is greater than 7/17...

A 3: Find a fraction which is greater than 7/17 but less than 5/12

I am surprised nobody took the easy way out. While 169/408 certainly works, (5+7)/(17+12)=12/29 is much easier to find. Of...
Forum: Data 2005-03-02, 04:33
Replies: 23
Views: 2,098
Posted By nfortino
Ok, I think further analysis makes it clear what...

Ok, I think further analysis makes it clear what is going on with some of the exponents. There are currently (as of 03-01-17) 7 exponents on the original list which have been reassigned....
Forum: Data 2005-03-01, 03:26
Replies: 23
Views: 2,098
Posted By nfortino
I agree that there are no exponents in the...

I agree that there are no exponents in the factoring queue which are not listed on primenet as having been factored less than indicated in nofactor, but there are 61 exponents (between 27256591 and...
Forum: Data 2005-02-25, 05:07
Replies: 23
Views: 2,098
Posted By nfortino
Here are the exponents for the February 23, 2005...

Here are the exponents for the February 23, 2005 data files, and the 25 Feb 2005 04:00 status.txt

Delete.txt has exponents which have been factored or double checked, but still have tests running....
Forum: Data 2005-02-24, 03:49
Replies: 23
Views: 2,098
Posted By nfortino
I can modify the script to filter out triple or...

I can modify the script to filter out triple or higher checks from the wrong queue list, but seeing as how we really don't know were the other exponents came from, it's probably a bad idea to delete...
Forum: Data 2005-02-21, 19:16
Replies: 23
Views: 2,098
Posted By nfortino
I had already done that. All tests that were been...

I had already done that. All tests that were been returned by an error prone machine (error rate of greater than .333 and at least 2 bad tests) were removed along with tests with tests with harmful...
Forum: Data 2005-02-21, 04:17
Replies: 23
Views: 2,098
Posted By nfortino
I could do that. I assume you want these reports...

I could do that. I assume you want these reports by e-mail, but I will post my original results here incase anyone wants to double check. I should be able to add it to automated scripts I have...
Forum: Data 2004-12-14, 16:19
Replies: 6
Views: 1,126
Posted By nfortino
That is weird. The factor in the database is not...

That is weird. The factor in the database is not a pure truncation, however. The last 9 digits of the false factor and the true factor are different. I assume this is because a pure truncation does...
Forum: Data 2004-12-14, 14:55
Replies: 6
Views: 1,126
Posted By nfortino
Bad Factor?

I found this factor in the most recent data files (12/12/04):
24742121,3047713721183690569
k = 61589580804

3047713721183690569=53*1009*56991112462997

As 53 is clearly not of the form 2kp+1,...
Forum: Miscellaneous Math 2004-11-20, 23:41
Replies: 8
Views: 909
Posted By nfortino
I believe he meant Eigenvalue. If that is what he...

I believe he meant Eigenvalue. If that is what he meant, and Eigenvalue of an n by n matrix is a scalar s such that Ax = sx for some n by 1 vector x.
Forum: Math 2004-10-23, 19:37
Replies: 9
Views: 2,829
Posted By nfortino
The factor you listed has already been found. A...

The factor you listed has already been found. A file containing all factors found by GIMPS can be found at the bottom of http://www.mersenne.org/status.htm
Forum: Math 2004-08-25, 16:18
Replies: 9
Views: 762
Posted By nfortino
While the multiple roots of the LL test are very...

While the multiple roots of the LL test are very interesting, they are not the answer to Dave's original question (or at least I don't think so). I assume he was asking about how the rotation of the...
Forum: Software 2004-08-25, 16:01
Replies: 15
Views: 1,188
Posted By nfortino
These numbers come from the FFT size required for...

These numbers come from the FFT size required for each exponent. However, these numbers should not concern you unless you are specifically looking to do p-1 work. In general, you should allocate as...
Forum: Math 2004-08-24, 16:20
Replies: 9
Views: 762
Posted By nfortino
From http://www.mersenne.org/math.htm GIMPS...

From http://www.mersenne.org/math.htm

GIMPS double-checking goes a bit further to guard against programming errors. Prior to starting the Lucas-Lehmer test, the S0 value is left-shifted by a...
Showing results 1 to 25 of 165

 
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