#1667 hgfred([1],[-5.2],x);

closed
nobody
None
5
2009-06-01
2009-05-15
No

I think this should not be undefined:

(%i7) hgfred([1],[-5.2],x);
(%o7) und

but

(%i10) hgfred([1],[b],x);
(%o10) (b-1)*%gammagreek(b-1,x)*x^(1-b)*%e^x

Discussion

  • Raymond Toy

    Raymond Toy - 2009-05-15

    Sorry, I don't follow. How is the first related to the second? Are you saying the second should ask if b is a negative integer and return undefined?

     
  • Barton Willis

    Barton Willis - 2009-05-29

    Maybe you misread the input as hgfred([1], [-5,2],x) (comma instead of period). Of course
    hgfred([1], [-5,2],x) is undefined, but hgfred([1], [-5.2],x) is defined.

     
  • Raymond Toy

    Raymond Toy - 2009-06-01

    Yes, I misread the 5.2 and 5 comma 2.

    A proposed fix that makes maxima not return und is to modify hyp-negp-in-l so that the implementation actually matches the comment that that function looks for negative integers. The code was checking for any negative number.

    With that change, maxima returns a 1F1 form. It won't return the gammagreek form because 1.0 is not an integer. Making maxima treat 1.0 as an integer is more controversial and I don't think we should do that.

     
  • Raymond Toy

    Raymond Toy - 2009-06-01
    • status: open --> closed
     
  • Raymond Toy

    Raymond Toy - 2009-06-01

    Fixed in CVS, hyp.lisp, rev 1.104, as suggested.

     

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