sign or conjugate bug



Hello Barton,

I do not think that we have a bug in the conjugate function. Furthermore, I
think we have no bug in the $sign function. The feature you need is not
implemented. The $sign function is not implemented in a way which allows to
handle complex expressions correctly.

Some time ago I worked a lot with the code of the $sign function, because I was
interested to get a better support for complex expressions like yours.

Thus, I have implemented code to extend $sign to give full support for complex
expressions. I have already posted some results on this mailing list. See:
[Maxima] Complex mode for $sign. Perhaps, we should come back to the suggested
code and implement full support for complex expressions.

Dieter Kaiser

-----Urspr?ngliche Nachricht-----
Von: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu] Im
Auftrag von Barton Willis
Gesendet: Freitag, 31. Oktober 2008 13:39
An: maxima at math.utexas.edu
Betreff: [Maxima] sign or conjugate bug

Does anybody know of a workaround or fix for the bug:

OK:

 (%i1) conjugate(sqrt(1-x^2)) - sqrt(1-x^2);
 (%o1) conjugate(sqrt(1-x^2))-sqrt(1-x^2)

Not OK:

 (%i2) sign(%);
 (%o2) zero

This could be a conjugate bug, not a sign bug.

Barton

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