complex conjugation

[Richard B. Kreckel]

Hi Andrius,

On Sat, 22 Nov 2003, Andrius Kurtinaitis wrote:
> it appears that the GiNaC expressions do not support the complex
> conjugation... :-(
> I need it,

It would be helpful (for us and yourself, probably) to quickly whip up a
list of what exactly you want to do with the conjugation.  On numeric
types it's clear.  On polynomials, there wouldn't be much you can do,
probably, because you cannot just stick assumptions on free symbols.  On
other functions without any free symbols involved, what would you expect?
Would you expect a transformation like this one being performed by the
evaluator?
    conjugate(sin(2))  ->  sin(2)
Oops!  Knowledge about sin() would be needed...

>            but I do not know yet how to implement it.

Maybe the best approach would be as an ordinary pseudofunction just like
abs() or csgn().  If you want transformations like the above you would
have to hand up information like "I am real" or "I am purely imaginary"
from inner pseudofunctions to their outer wrapping pseudofunction.  You
would have to implement that as well, since it's not there yet.  For
simple cases this isn't very difficult.

> Has anybody tried to do this?
> Clearly conjugation is a function ;-)
> Ok, i'll try to read the tutorial. Let's see if I get this working...

Luck
   -richy.
-- 
Richard B. Kreckel
<Richard.Kreckel at GiNaC.DE>
<http://www.ginac.de/~kreckel/>