#788 sign(infinity) & sign(infinity^2)

closed
nobody
Lisp Core (471)
5
2009-03-06
2005-09-26
No

For consistency with sign(%i) --> error, I think
sign(infinity) should also signal an error. But it
doesn't:

(%i1) sign(infinity);
(%o1) PNZ

No debate about these --- PZ is a bogus
evaluation for sign(infinity^2):

(%i2) sign(infinity^2);
(%o2) PZ
(%i4) ?csign(infinity^2);
(%o4) PZ

Barton

Discussion

  • Robert Dodier

    Robert Dodier - 2005-10-08
    • labels: --> Lisp Core
     
  • Robert Dodier

    Robert Dodier - 2005-10-08

    Logged In: YES
    user_id=501686

    I would be happier with sign(infinity) => und (likewise
    sign(%i) => und). Calling merror pretty much precludes
    further progress; returning something or throwing something
    at least makes it possible to keep going. For what it's worth.

     
  • Dieter Kaiser

    Dieter Kaiser - 2009-03-06
    • status: open --> closed
     
  • Dieter Kaiser

    Dieter Kaiser - 2009-03-06

    With Maxima 5.17.0 we no longer get the reported results. Maxima throws an error, but not UND as suggested in the post below:

    (%i7) sign(infinity);
    sign: sign of infinity is undefined.
    -- an error. To debug this try debugmode(true);
    (%i8) sign(infinity^2);
    sign: sign of infinity is undefined.
    -- an error. To debug this try debugmode(true);
    (%i10) ?csign(infinity^2);
    sign: sign of infinity is undefined.
    -- an error. To debug this try debugmode(true);

    Closing this bug report.

    Dieter Kaiser

     

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