[GiNaC-devel] Derivative of abs()

[Jan]

Dear Vladimir,

> You formula does not work for abs(f) and complex values. I have
>   proposed here 
>
> http://www.ginac.de/pipermail/ginac-devel/2013-November/002053.html
>
>   another formula:
>
> (abs(f))'=(f'*f.conjugate()+f*f'.conjugate())/2/abs(f)
>
>   It requires some revision of function class and new method of
>   derivation going beyond the chain rule. I proposed to do this job, but
>   do not remember my email to be answered.
>
>   Best wishes,
>   Vladimir
> --
I hadn't thought of complex numbers, but then I'm not much of a
mathematician anyway.

About the responsiveness of the list, I made the same experience. A
while ago I volunteered to contribute some code, but nobody ever
answered to my suggestions.

Greetings,
Jan