mtsieve - Page 43

pepi37 · 2020-11-28, 22:10

Quote:

Originally Posted by ATH

Ok, thanks.

I did check for a new version before posting, but I checked in post #1 in this thread which links to:
https://mersenneforum.org/rogue/mtsieve.html

and that page still has link to mtsieve 1.9.6, maybe add the sourceforge link to that page?

https://sourceforge.net/projects/mts....6.7z/download

rogue · 2020-11-29, 00:00

I updated the html months ago, but apparently never posted it. The mtsieve home page has been updated.

ATH · 2020-11-29, 06:46

fkbnsieve v1.3 (mtsieve 2.0.6) works, but seems very slow compared to when I used it before. The p=3 step is running very slowly even with c-ranges of a few million only removing a few thousands factors per second.

Code:

fkbnsieve.exe -c 1 -C 1000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 972437.  Remaining terms: 27563.  Time: 48.53 seconds.

fkbnsieve.exe -c 1 -C 2000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 1944946.  Remaining terms: 55054.  Time: 190.56 seconds.

fkbnsieve.exe -c 1 -C 4000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 3889879.  Remaining terms: 110121.  Time: 758.98 seconds.

fkbnsieve v1.1:
fkbnsieve.exe -c 1 -C 4000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336328.  Factors found: 972437.  Remaining terms: 27563.  Time: 1.73 seconds.

This last one taking 758.98s takes only 1.73s in fkbnsieve v1.1 (mtsieve 1.8.4)

I'll just use fkbnsieve v1.1 for now, but I wanted to report it in case it is a bug.

rogue · 2020-11-29, 14:21

Quote:

Originally Posted by ATH

fkbnsieve v1.3 (mtsieve 2.0.6) works, but seems very slow compared to when I used it before. The p=3 step is running very slowly even with c-ranges of a few million only removing a few thousands factors per second.

Code:

fkbnsieve.exe -c 1 -C 1000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 972437.  Remaining terms: 27563.  Time: 48.53 seconds.

fkbnsieve.exe -c 1 -C 2000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 1944946.  Remaining terms: 55054.  Time: 190.56 seconds.

fkbnsieve.exe -c 1 -C 4000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336332.  Factors found: 3889879.  Remaining terms: 110121.  Time: 758.98 seconds.

fkbnsieve v1.1:
fkbnsieve.exe -c 1 -C 4000000 -P 400000000 -s "1*2^65+c"
Primes tested: 21336328.  Factors found: 972437.  Remaining terms: 27563.  Time: 1.73 seconds.

This last one taking 758.98s takes only 1.73s in fkbnsieve v1.1 (mtsieve 1.8.4)

I'll just use fkbnsieve v1.1 for now, but I wanted to report it in case it is a bug.

I will have to look into what changed. If I had to suspect anything I would suspect the the older version did not have working factor validation.

pepi37 · 2020-11-29, 21:17

I cannot find fkbnsieve.exe in latest release ( in 7z file)
Also can srsieve2 sieve in parallel few sequences or just one by one?

VBCurtis · 2020-11-29, 22:21

If by "in parallel" you mean multi-threaded, yep.

pepi37 · 2020-11-29, 22:34

Quote:

Originally Posted by VBCurtis

If by "in parallel" you mean multi-threaded, yep.

No :)
I mean to sieve few sequence in same time ( like I can with sr2sieve)

rogue · 2020-11-29, 23:33

Quote:

Originally Posted by pepi37

No :)
I mean to sieve few sequence in same time ( like I can with sr2sieve)

Yes. You can use -s multiple times on the command line.

rogue · 2020-11-29, 23:39

Quote:

Originally Posted by rogue

I will have to look into what changed. If I had to suspect anything I would suspect the the older version did not have working factor validation.

The slowdown is due to a change to the factor verification code. Previously it would compute k*b^n once regardless of how many c that are divisible by p. I changed to recompute k*b^n for each factor. The reason is that I wanted to guarantee the use of a different algorithm for the verification of a factor. I might be able to make changes to help on the speed, but I'll have to look into it.

In short, this will only impact you for small p. Once p > maxC - minC, the speed will be the same.

pepi37 · 2020-11-29, 23:40

Quote:

Originally Posted by rogue

Yes. You can use -s multiple times on the command line.

Great news! Save alot of time!
Thanks!

pepi37 · 2020-12-01, 22:12

Rogue one suggestion for all sieve programs in mtsieve package.

When using with -I -A ( apply factors and exit) add simple logic to check is factors really factors.
I accidentally make wrong copy paste and srsieve2 remove candidate regardless fact ( because error) that was not good factor for that candidate.

2020-11-29, 21:17	#467
pepi37 Dec 2011 After milion nines:) 2·5·139 Posts	I cannot find fkbnsieve.exe in latest release ( in 7z file) Also can srsieve2 sieve in parallel few sequences or just one by one? Last fiddled with by pepi37 on 2020-11-29 at 21:30

2020-11-29, 00:00	#464
rogue "Mark" Apr 2003 Between here and the 14037₈ Posts	I updated the html months ago, but apparently never posted it. The mtsieve home page has been updated.

2020-11-29, 22:21	#468
VBCurtis "Curtis" Feb 2005 Riverside, CA 2³×577 Posts	If by "in parallel" you mean multi-threaded, yep.

2020-12-01, 22:12	#473
pepi37 Dec 2011 After milion nines:) 2·5·139 Posts	Rogue one suggestion for all sieve programs in mtsieve package. When using with -I -A ( apply factors and exit) add simple logic to check is factors really factors. I accidentally make wrong copy paste and srsieve2 remove candidate regardless fact ( because error) that was not good factor for that candidate.