20060108, 12:52  #188 
"Sander"
Oct 2002
52.345322,5.52471
10010100101_{2} Posts 
I think i found a new record size octoproth:
n=239, kmin=1, kmax=1000000000000000 237534540236595 239 689532548527515 239 988916004684825 239 n=240, kmin=1, kmax=1000000000000000 n=244, kmin=1, kmax=10000000000000 n=245, kmin=1, kmax=10000000000000 n=246, kmin=1, kmax=10000000000000 n=247, kmin=1, kmax=100000000000000 
20060108, 13:52  #189  
Aug 2005
Brazil
2×181 Posts 
Quote:
P.S: The executable works fine! Thanks! Last fiddled with by fetofs on 20060108 at 13:55 

20060108, 16:54  #190 
Nov 2003
3622_{10} Posts 
Found the new largest octo with 116 digits in k*2^n+1 bitwins and 102 digits in 2^n+k, 2^(n+1)+k members. All 8 numbers certified primes.
157715286549765 336 [160T] The following n's are checked to 100T, no octos: 332335, 337348. The following checked to 50T, no octos: 349350. Also, n=232 checked to 400T, no octos. n=158160 in progress, will post results soon. 
20060108, 17:54  #191 
Nov 2003
2×1,811 Posts 
BTW, I couldn't verify that ver. 3.0 is 40% faster than ver. 2.0, on the contrary for n=336, kmin=100T, and kmax=111T, ver. 2.0 is faster on my AhtlonMP2000+ (1.67GHz) compiled by gcc without any optimization options and linked against libgmp.dll.a
ver. 2.0: 302 sec ver. 3.0: 306 sec (145880 prp tests, x=8) While I found the n=336 octo using modified ver. 2.0 with prp block similar to ver. 3.0 but without counting the number of prp tests. That one takes 299 sec. Finally, ver. 3.0 modified to do prp tests in increasing order of 8 octo members took 301 sec, or about 2% speed up. 
20060108, 18:07  #192 
"Sander"
Oct 2002
52.345322,5.52471
29·41 Posts 
My v3 with cpu optimizations was about 40% faster compared to v2 with no optimizations.

20060108, 19:16  #193  
"Robert Gerbicz"
Oct 2005
Hungary
2·7·103 Posts 
Quote:
Why you didn't use flags? These give you additional speedups. Quote:
An mpz_add_ui instruction takes constant number of clock cycles, say 5 then 145880 such additions takes about 1 million cycles Your computer' speed say about 5*10^9 cycles/sec so this computation cost is less than 0.001 sec. Compare this to the runtime=300 sec. Believe it or not. Note that I've tested octo 3.0 only on Windows and on that I've gotten about 40% speedup. This is P4 Celeron 1.7 GHz and L2 cache=128 Kbyte ,this is also very important for octo, because the current version is using about 550 Kbyte of memory, so this is not fit on my fast L2 cache and also Celeron isn't the best choice. Quote:
Quote:


20060108, 21:57  #194 
2·17·67 Posts 
xp
I cannot get any version to run, on XP pro SP2 without cygwin.
This is a no go for me then, darn.. Last fiddled with by TTn on 20060108 at 21:57 
20060108, 22:15  #195  
"Robert Gerbicz"
Oct 2005
Hungary
2×7×103 Posts 
octo version_3_5
Quote:
You can download from my homepage the newest version for windows: http://www.robertgerbicz.tar.hu/octo_3_5.exe Or see my attachment for the c source code. I've made a very small change. Version 3.0 is correct but this new version uses less prp tests, because there was some missed composites (I haven't deleted some numbers in the sieve which has got small prime factors, it means that there is no missed octoproths! for version 3.0 ) in the sieve ( this happens only in 3.0 ). You get small improvement, because sieving is much faster, but it is suggested to download the new version. 

20060109, 03:45  #196 
Nov 2005
10110110_{2} Posts 
Version 2.0:
"Faulting application octo2.exe, version 0.0.0.0, faulting module octo2.exe, version 0.0.0.0, fault address 0x00009144." "The application, C:\Documents and Settings\JoeDesktop\Desktop\octo2.exe, generated an application error The error occurred on 01/06/2006 @ 22:08:44.078 The exception generated was c000001d at address 00409144 (octo2)" Current version: Faulting application octo_3_5.exe, version 0.0.0.0, faulting module octo_3_5.exe, version 0.0.0.0, fault address 0x00008994. Are sure this program works on Athlon XPMobile processors? Those errors sound like unsupported features of the instruction set. Exception c000001d is generally illegal instructions according to my documentation. I'll try it on my P3 laptop but I'm pretty sure it will work on it. This is most certainly your version of GMP being compiled for another CPU. :) Last fiddled with by nibble4bits on 20060109 at 03:51 
20060109, 07:59  #197 
Jun 2003
Oxford, UK
2^{2}×13×37 Posts 
181185
n=181, kmin=1, kmax=200000000000000, version=3.0
Starting the sieve... Using the first 9 primes to reduce the size of the sieve array 152614043635305 181 The sieving is complete. n=182, kmin=1, kmax=200000000000000, version=3.0 Starting the sieve... Using the first 9 primes to reduce the size of the sieve array 127732547041365 182 The sieving is complete. n=183, kmin=1, kmax=180000000000000, version=3.0 Starting the sieve... Using the first 9 primes to reduce the size of the sieve array The sieving is complete. n=184, kmin=1, kmax=500000000000000, version=3.0 Starting the sieve... Using the first 9 primes to reduce the size of the sieve array 276221124938745 184 212311049145495 184 342826651623555 184 381356034701265 184 The sieving is complete. Will take on 185190 next Regards Robert Smith 
20060109, 08:00  #198 
Jun 2003
Oxford, UK
2^{2}×13×37 Posts 
185
pops forgot to show:
n=185, kmin=1, kmax=500000000000000, version=3.0 Starting the sieve... Using the first 9 primes to reduce the size of the sieve array 229673680116405 185 77793510170775 185 The sieving is complete. Robert Smith 
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