> From: Dieter Kaiser
>
> I am interested in solution b) and have added some code to
> sdiffgrad with the following functionality:
>
> 1. Allow a lambda expression to define a derivative.
> 2. Allow the value NIL, when we do not know the derivative.
>
> I have taken the main idea from the code for the integral-property.
I think this is a good idea. I tried several approaches as I wrote the
code for lambda expressions in the integral property. I was amazed
that the changes to the maxima code were so small. There were a few
initial problems but they were easily resolved. Once it was working
then
it was trivial and safe to add integrals for special functions, as the
additional code is restricted to property of the special function.