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Re: Problem with pariGP's factor() function

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  • mikeoakes2
    ... After about 10 times more usage, with Pari-GP Version 2.5.0, exactly one failure has occurred, in this section of code:-
    Message 1 of 49 , Jan 2, 2012
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      --- In primenumbers@yahoogroups.com, "mikeoakes2" <mikeoakes2@...> wrote:
      >
      > --- In primenumbers@yahoogroups.com, "djbroadhurst" <d.broadhurst@> wrote:
      > > default(primelimit,10^6);
      > > saferfactor(x)=trap(,factor(x,0),factorint(x,1));
      > > should be both fast and safe, for your 12-digit targets,
      > > since it combines all three of the offered remedies,
      > > each of which is inferior by itself.

      > I have been running this code for 18 hours now, on 4 cores
      > @100% loading, which has activated it about 1.5 billion times -
      > and all without a whisper of a problem.

      After about 10 times more usage, with Pari-GP Version 2.5.0, exactly one failure has occurred, in this section of code:-

      saferfactor(x)=trap(,factor(x,0),factorint(x,1));
      {write_line(k,x)=f=saferfactor(kk);...

      The error is not repeatable in debug mode, witness this transcript:-

      *** at top-level: ...)>=Kmin)&&(abs(k)<=Kmax),write_line(k,x));y+=
      *** ^--------------------
      *** in function write_line: ...nd,pow_str,len=0,s="");f=
      *** saferfactor(kk);facs
      *** ^--------------------
      *** in function saferfactor: trap(,factor(x,0),factorint(x,1))
      *** ^---------------
      *** factorint: bug in PARI/GP (Segmentation Fault), please report
      *** Break loop: type 'break' to go back to GP
      break> kk
      359507948009
      break> saferfactor(6)
      [2 1]
      [3 1]
      break> saferfactor(kk)
      [7 1]
      [59 1]
      [27031 1]
      [32203 1]

      The code has been runnng exclusively on 12-digit integers, of which there are a lot(!); about 2% of them have been processed to date.

      So, it looks as if there is yet one more strand to the clutch of pari coding bugs in this area.

      Mike
    • mikeoakes2
      ... After about 10 times more usage, with Pari-GP Version 2.5.0, exactly one failure has occurred, in this section of code:-
      Message 49 of 49 , Jan 2, 2012
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        --- In primenumbers@yahoogroups.com, "mikeoakes2" <mikeoakes2@...> wrote:
        >
        > --- In primenumbers@yahoogroups.com, "djbroadhurst" <d.broadhurst@> wrote:
        > > default(primelimit,10^6);
        > > saferfactor(x)=trap(,factor(x,0),factorint(x,1));
        > > should be both fast and safe, for your 12-digit targets,
        > > since it combines all three of the offered remedies,
        > > each of which is inferior by itself.

        > I have been running this code for 18 hours now, on 4 cores
        > @100% loading, which has activated it about 1.5 billion times -
        > and all without a whisper of a problem.

        After about 10 times more usage, with Pari-GP Version 2.5.0, exactly one failure has occurred, in this section of code:-

        saferfactor(x)=trap(,factor(x,0),factorint(x,1));
        {write_line(k,x)=f=saferfactor(kk);...

        The error is not repeatable in debug mode, witness this transcript:-

        *** at top-level: ...)>=Kmin)&&(abs(k)<=Kmax),write_line(k,x));y+=
        *** ^--------------------
        *** in function write_line: ...nd,pow_str,len=0,s="");f=
        *** saferfactor(kk);facs
        *** ^--------------------
        *** in function saferfactor: trap(,factor(x,0),factorint(x,1))
        *** ^---------------
        *** factorint: bug in PARI/GP (Segmentation Fault), please report
        *** Break loop: type 'break' to go back to GP
        break> kk
        359507948009
        break> saferfactor(6)
        [2 1]
        [3 1]
        break> saferfactor(kk)
        [7 1]
        [59 1]
        [27031 1]
        [32203 1]

        The code has been runnng exclusively on 12-digit integers, of which there are a lot(!); about 2% of them have been processed to date.

        So, it looks as if there is yet one more strand to the clutch of pari coding bugs in this area.

        Mike
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