#1035 limit of algebraic when algebraic : true

closed
nobody
7
2007-09-02
2006-12-01
No

(%i1) x*(sqrt(1+x^2)-x);
(%o1) x*(sqrt(x^2+1)-x)
(%i2) limit(%,x,inf), algebraic : true;
Quotient by a polynomial of higher degree

Discussion

  • Barton Willis

    Barton Willis - 2006-12-02

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    When gcd : 'spmod, this bug goes away:

    (%i7) limit(x*(sqrt(1+x^2)-x),x,inf), algebraic : true, gcd : 'spmod;
    (%o7) 1/2

     
  • Robert Dodier

    Robert Dodier - 2006-12-27

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    Assign category & increase priority.

     
  • Robert Dodier

    Robert Dodier - 2006-12-27
    • labels: --> Lisp Core - Polynomials
    • priority: 5 --> 7
     
  • Dan Gildea

    Dan Gildea - 2007-07-31

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    Seems to be caused by subresgcd being called with a cre that is not really a
    polynomial: the coeffecients contain the top-level variable. Possible solution
    would be to test for this condition, then call another gcd algorithm, or just
    return 1 as gcd. Any suggestions on how to do the test?

     
  • Dan Gildea

    Dan Gildea - 2007-09-02

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    fixed in rat3c.lisp rev 1.18
    add checks to subresgcd and redgcd for cases where the coefficients
    of the CRE contain the main variable.

    (%i2) limit(x*(sqrt(1+x^2)-x),x,inf), algebraic : true, gcd : subres;
    (%o2) 1/2

     
  • Dan Gildea

    Dan Gildea - 2007-09-02
    • status: open --> closed
     

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