[GiNaC-devel] Derivative of conjugated is conjugated of derivative.

[Richard B. Kreckel]

Dear Alexei,

On 11/05/2013 09:52 AM, Vladimir V. Kisil wrote:
> 	Dear Richard,
> 
>>>>>> On Tue, 05 Nov 2013 09:02:12 +0100, "Richard B. Kreckel" <kreckel at ginac.de> said:
> 
>     RK> Hi Vladimir, On 11/05/2013 08:11 AM, Vladimir V. Kisil wrote:
>     >> Further to my previous patch on functions derivatives, this small
>     >> patch adds the rule
>     >> 
>     >> conjugate(f)'=conjugate(f')
> 
>     RK> This patch is inconsistent with the rest of
>     RK> inifcns_trans.cpp. Please search for "branch cut" inside that
>     RK> file.
> 
>     RK> Now, subs(log(conjugate(x))-conjugate(log(x)), x==-1) evaluates
>     RK> to 2*I*Pi. With your patch, it would evaluate to 0.
> 
>     I could not see how this expression is connected to derivative. It
>   does evaluates to (2*I)*Pi with the proposed patch. 

You are right. Sorry for misinterpreting your patch.

Still, I'm not convinced that the general transformation conjugate(f)'
-> conjugate(f') is generally correct. Is it correct even on branch
cuts? If you have a prove, please try writing it in your patch so this
will be clear to people reading this section later on.

Best wishes
   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>