#180 factor infinite loop

closed
nobody
5
2007-08-18
2002-11-08
No

expr: (%i*a-1)/(a^2+1)^2

factor(expr) runs forever

but

factor((%i*a-1)/(a^2+1)) works fine, as does gfactor(expr)

Discussion

  • Andrej Vodopivec

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    user_id=1179910

    This is a bug in the simplifier:

    ratsimp(expr), ratfac=true;

    goes to infinite loop. The infinite loop is in function
    lgcd1 in lesfac.lisp:

    aloop
     \(cond \(\(setq t1 \(testdivide ai c\)\)
        \(setq ai t1 d1 \(f1+ d1\)\)
        \(go aloop\)\)\)
    

    ai=a*%i-1 and c=%i. Since division by %i is multiplication
    by -%i, maxima keeps dividing ai with c. It is not clear if
    maxima should never get to this loop or if testdivide should
    not perform the division by %i.

    Andrej

     
  • Robert Dodier

    Robert Dodier - 2006-07-01
    • labels: --> 460522
     
  • Robert Dodier

    Robert Dodier - 2006-09-09
    • labels: 460522 --> Lisp Core - Polynomials
     
  • Dan Gildea

    Dan Gildea - 2007-08-03

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    user_id=1797506
    Originator: NO

    Seems ok in 5.12.0.

     
  • Dan Gildea

    Dan Gildea - 2007-08-03
    • status: open --> pending
     
  • SourceForge Robot

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    user_id=1312539
    Originator: NO

    This Tracker item was closed automatically by the system. It was
    previously set to a Pending status, and the original submitter
    did not respond within 14 days (the time period specified by
    the administrator of this Tracker).

     
  • SourceForge Robot

    • status: pending --> closed
     

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