mtsieve

[rogue]

I have released 2.2.0:

   framework:
      Updated OpenCL on Windows.  See makefile for details.
      Updated primesieve to 7.6.
   
   psieve, psievecl:  version 1.4
      Some refactoring to support OpenCL worker.
      First release of psievecl.
      Verify factors from -I input file

   srsieve2, srsieve2cl:  version 1.5.1
      Fixed bug that was introduced in the refactoring of 1.5 that impacts generic sieving
      while using multiple threads.
      Added -R to remove sequences.  Use -Rk*b^n+c format to remove a single sequence or
      use -R with a file that has multiple sequences.  This is not tested yet.

psievecl is about 20x faster than psieve. The main slowdown is factor validation, which is less noticeable as factors become more sparse.

One odd behavior is that I noticed that srsieve2cl is slower than the previous release, but I do not know why. Even after reverting the framework changes for the release it was slower. I thought it was the update to OpenCL or primesieve, but reverting to the older versions of those made no difference. I'm likely missing something, but I don't know what.

I'm hoping that someone is willing to give the -R option with srsieve2 a spin.

[Happy5214]

Originally Posted by rogue

I'm hoping that someone is willing to give the -R option with srsieve2 a spin.

No luck:

$ ./srsieve2 -i b2_n.abcd -o b2_n.abcd -R "658687*2^n-1"
srsieve2 v1.5.1, a program to find factors of k*b^n+c numbers for fixed b and variable k and n
2018 terms for sequence 658687*2^n-1 have been removed
Must use generic sieving logic because there is more than one sequence
Sieving with generic logic for p >= 982453051
Fatal Error:  Expected 62636 terms when building sequences, but counted only 60618

Input file attached (with .txt extension added).

[rogue]

Originally Posted by Happy5214

No luck:

$ ./srsieve2 -i b2_n.abcd -o b2_n.abcd -R "658687*2^n-1"
srsieve2 v1.5.1, a program to find factors of k*b^n+c numbers for fixed b and variable k and n
2018 terms for sequence 658687*2^n-1 have been removed
Must use generic sieving logic because there is more than one sequence
Sieving with generic logic for p >= 982453051
Fatal Error:  Expected 62636 terms when building sequences, but counted only 60618

Input file attached (with .txt extension added).

That will be easy to fix. When the sequence is removed the code isn't decrementing il_TermCount.

[rogue]

I have released 2.2.1. Here are the changes:

[quote]
framework: no changes

gfndsieve, gfndsievecl: version 2.0
Moved GFN divisor testing to GFNDivisorTester class so that GFNDivisorApp is smaller
and so that future support of non-x86 is easier since GFNDivisorTester
calls a number of x86 asm methods directly.

For gfndsievecl do not report any terms with factors < 50. This reduces the size
needed for the buffer that is used to report factors.

Added -r and -R options to support functionality similar to ppsieve.
-r will not generate a bitmap for tracking terms. It will only generate an
output file of factors.
-R is used with -r. If a term has a factor below 32767 (the default value),
then the program will not output any factors for the term.
-r and -x are mutually exclusive with -r overriding -x.

Added various speed improvements.

srsieve2, srsieve2cl: version 1.5.2
Fixed issue with CisOne logic as it tries to rebuild sequences when there are
multiple sequences as that is not yet supported.
[quote]

In what limited performance testing I have done it appears that gnfdsievecl with -r is about 5x faster than the OpenCL version of ppsieve. I think some of that is due to using a much higher value for -S in gnfdsievecl than what ppsievecl does, but that doesn't explain the entirely of the speed gain. The CPU only version is about 3x slower than ppsieve, but that is due to a lot of fine-tuned assembler in the ppsieve CPU code. I don't expect anyone to use it for that, but at the same time gfndsieve should be about 50% faster for typical gfn divisor sieving.

[YaoPlaysMC]

Can someone make a program for sieving sequences of the form k₁*b₁^n+k₂*b₂^n+c with variable n?