Renewed discussion about Q'slew behavior with a discontinuous Q

For the following pseudo example,
quantity Q, Q2 real :=0.0;
if (xxx)
    Q == 1.0;
else
    Q == 2.0;

Q2 == Q'slew(100, -100);

Suppose, quantity Q has an immediate jump at t0 from 1.0 to 2.0;

xxx: some digital condition.
Q, Q2 are quantities.

So the key question is that how should be deal with this kind of Dirac
Q'DOT?
a) Ignore it and treat it as zero:
        (My opinion: 1. Q'slew don't have the desired effect under this
interpretation.
                             2. Will it be a concern that Q'DOT value is
not defined in this case?)
b) treat it as a very very large value (Dirac function):
        (My opinion: It leads to my previous observation where current
Q'SLEW behavior in LRM is problematic)
c) Don't allow Q to be discontinuous
        (My opinion: too restrictive on quantity)
d) any other interpretation/suggestions .... ???

The attached docx contains my interpretation of the LRM behavior with
illustrated figure. I also explain what may be the should-be behavior in
this case and another option to deal with this if my interpretation of LRM
is accurate.

Another view is that we should make the righ-limit and left-limit of Q'DOT
be zero in this case and details is attached in slew_discussion2.pdf

The simple example is in attachement slew_discussion.vhd

Please share your thoughts on this issue so that we could clean this up the
next version of VHDL-AMS.


Thanks,
Zhichao

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