Z Transform problem ?

[parisse]

I can obviously not adopt the notation of one domain if it is in conflict with other domains. For example, everybody is using i for sqrt(-1) on the calc despite the usual notation in physics is j. This means you will never have a u for the Heaviside function. I don't know if I'll modify the current code to replace discrete Dirac with Heaviside, because it's programming work in a field I do not use at all and it would certainly raise new bugs.
I really believe that the interest of having ztrans and invztrans in a CAS is not to have a table lookup replacement, it's to make the real computations, i.e. partial fraction decomposition for invztrans. This should be useful for students who really understand what's happening because they can make themselve the final adjustements to adapt to their field.