Half-angle-simplification of trig functions



Hello Stefano,

Yes I think it is the same problem. 

If I use an intervall (0,2*%pi) the simplification of sin(x/2) works well. If I
use an intervall (0,%pi) the simplifcation of cos(x/2) works well. But now the
simplification of sin(x/2) fails. If I use an intervall (0,3.0) both
simplifications works well.

I think this is a bug of assume with %pi as a value. I do not know the reason of
the bug. I will have a deeper look into the code to find it.

Dieter Kaiser

-----Urspr?ngliche Nachricht-----
Von: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu] Im
Auftrag von Stefano Ferri
Gesendet: Dienstag, 6. Januar 2009 11:17
An: maxima at math.utexas.edu
Betreff: Re: [Maxima] Half-angle-simplification of trig functions

In your code there are some "assume" in wich you used integer multiples 
of %pi, like

(assume(x1>0,x1<2*%pi),done);

did it work correctly? You said

> Remark: Better would be %pi as upper limit, but this does not work!
> Is this related to known problems with assume?

Your code needs to bound variables within multiples of %pi, are the problems you
mentioned the ones reported here?

http://sourceforge.net/tracker/index.php?func=detail&aid=2477795&group_id=4933&a
tid=104933

I reported this as a bug (if it is a bug, but I think so...)

Stefano

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