mtsieve

[rogue]

Originally Posted by Happy5214

I only needed one program, so I used "make srsieve2". It compiled, but failed to link (specifically mentioning -lOpenCL).

Line 386 of the Makefile (the rule for srsieve2) is:

$(CC) $(CPP_FLAGS) $(OPT_CPP_FLAGS) $(LD_FLAGS_OPENCL) -o $@ $^ $(LD_FLAGS)

I see. I have committed a change to the makefile. See if that resolves this issue.

[Citrix]

A bug with twinsieve. The program does not abort if all terms have been sieved.

twinsieve.exe -W16 -k2 -K7000 -n7000 -b2 -p3 -P10e14 -fA -t1
twinsieve v1.6.1, a program to find factors of k*b^n+1/-1 numbers for fixed b and n and variable k
Sieve started: 3 <= p <= 1e15 with 3499 terms (3 < k < 6999, k*2^7000) (expecting 3388 factors)
Increasing worksize to 10000000 since each chunk is tested in less than a second
Increasing worksize to 50000000 since each chunk is tested in less than a second
  p=43401596201, 38.24M p/sec, 3499 factors found at 51.62 f/sec (last 1 min), 0.0% done. ETC 2023-07-02 23:35
Decreasing worksize to 25000000 since each chunk needs more than 5 seconds to test
...

[rogue]

Originally Posted by Citrix

A bug with twinsieve. The program does not abort if all terms have been sieved.

twinsieve.exe -W16 -k2 -K7000 -n7000 -b2 -p3 -P10e14 -fA -t1
twinsieve v1.6.1, a program to find factors of k*b^n+1/-1 numbers for fixed b and n and variable k
Sieve started: 3 <= p <= 1e15 with 3499 terms (3 < k < 6999, k*2^7000) (expecting 3388 factors)
Increasing worksize to 10000000 since each chunk is tested in less than a second
Increasing worksize to 50000000 since each chunk is tested in less than a second
  p=43401596201, 38.24M p/sec, 3499 factors found at 51.62 f/sec (last 1 min), 0.0% done. ETC 2023-07-02 23:35
Decreasing worksize to 25000000 since each chunk needs more than 5 seconds to test
...

I don't think it has a check for that. I will have to take a look.

[Citrix]

I don't think the twinsieve 1.6.1 in the latest release is working correctly. For n=7001 it produces the following which has small factors (3 and 11)

ABC $a*2^7001+1 & $a*2^7001-1 // Sieved to 41213171663
4879

[pepi37]

As always if I take new CRUS reservation, and that reservation has no sieve file I run it with srsieve2. When pass some level I switch to srsieve2cl and run it on GPU so I can free CPU to testing. Afer that I do some very light P-1 on mprime so I remove some extra factors.
Last two times using latest srsieve2 build regardless fact I sieve to 2e13 I found with P-1 that some factors are not found with srsieve2 or better to say factors are missed..
So that is not big deal, but on the other side, I dont know how many of them are missed.
I like srsieve2 since it run MT and very nice use all cores so efficiency is very high but to be prepared some factors can be missed.

For S773 missed factors found by P-1 was

2*773^466005+1 has a factor: 4153116809
2*773^353085+1 has a factor: 71389978241
2*773^428381+1 has a factor: 396476137649
2*773^457997+1 has a factor: 411344474899

Every one here can confirm or deny my statement, run that sequence from 350K to 500K with srsieve2.
If it is my error then I apologize to Rogue, but I think srsieve2 miss some factors.

[gd_barnes]

Originally Posted by pepi37

As always if I take new CRUS reservation, and that reservation has no sieve file I run it with srsieve2. When pass some level I switch to srsieve2cl and run it on GPU so I can free CPU to testing. Afer that I do some very light P-1 on mprime so I remove some extra factors.
Last two times using latest srsieve2 build regardless fact I sieve to 2e13 I found with P-1 that some factors are not found with srsieve2 or better to say factors are missed..
So that is not big deal, but on the other side, I dont know how many of them are missed.
I like srsieve2 since it run MT and very nice use all cores so efficiency is very high but to be prepared some factors can be missed.

For S773 missed factors found by P-1 was

2*773^466005+1 has a factor: 4153116809
2*773^353085+1 has a factor: 71389978241
2*773^428381+1 has a factor: 396476137649
2*773^457997+1 has a factor: 411344474899

Every one here can confirm or deny my statement, run that sequence from 350K to 500K with srsieve2.
If it is my error then I apologize to Rogue, but I think srsieve2 miss some factors.

Were the factors missed in srsieve2 or srsieve2cl ?

[pepi37]

Originally Posted by gd_barnes

Were the factors missed in srsieve2 or srsieve2cl ?

First two, small ones, 100% with srsieve2.

[gd_barnes]

Originally Posted by pepi37

First two, small ones, 100% with srsieve2.

Can you post the exact command that you ran? I will see if I can duplicate the problem.

We need to know the following:
1. How many cores were you running?
2. Were you using Legendre tables?
3. Were you running specifically -s "2*773^n+1" stand-alone or with the multiple k's remaining on base S773?
4. Confirming since you stated you were running the latest srsieve2: Were you running version 1.7.1?

[Happy5214]

Originally Posted by gd_barnes

Can you post the exact command that you ran? I will see if I can duplicate the problem.

We need to know the following:
1. How many cores were you running?
2. Were you using Legendre tables?
3. Were you running specifically -s "2*773^n+1" stand-alone or with the multiple k's remaining on base S773?
4. Confirming since you stated you were running the latest srsieve2: Were you running version 1.7.1?

This is all useful information to determine the exact parameters.

My testing with Legendre tables, 3 cores, -s "2*773^n+1" and non-GPU version 1.7.1 directly built (on Linux) from SVN 294 could not reproduce it (i.e. it found all 4 factors listed, and specifically had 634 remaining at 5e11), but different parameters may result in a bug.

[gd_barnes]

I ran the following command on only 1 core to P=1e11:
srsieve2 -P100e9 -n350e3 -N500e3 -W1 -O factors.txt -s "2*773^n+1"

With only 1 sequence, srsieve2 will default to using Legendre tables, which it did here.

It found 149,333 factors leaving 668 remaining including the first two in your post.

I then ran old srsieve/sr1sieve for the same and had them output all factors. The factor and final sieve files both matched the srsieve2 run.

So...no luck duplicating the problem there.

I'm now running srsieve2 on 2 cores with all 5 k's remaining for base S773. I had to tell it to use Legendre tables with the -l switch since there was more than one sequence. I'll post results when done.

[gd_barnes]

The problem occurs when running more than one sequence with Legendre tables. It's definitely missing factors.

I have experienced this before and thought it was something I was doing wrong.

I ran this command:
srsieve2 -P100e9 -n350e3 -N500e3 -W2 -l10e3 -O factors.txt -s input-S773.txt

Where input-S773.txt contains the 5 sequences for CRUS base S773.

It did not find the first two factors that Pepi mentioned and appears to miss many more than that.

I then ran the above command without the -l switch. It has reached P=10e9 already and quickly found the 1st factor that Pepi mentioned. It will continue to P=100e9 to attempt to find the second factor that he listed.

I haven't checked if it would have the problem running only 1 core.

I don't have time to post many details right now. I'll post a detailed analysis of the situation in the morning.

My current suggestion: Don't run srsieve2 with the Legendre tables on more than one sequence.