idt assert

I remember a few years ago at Antrim, I used idt with assert to model a 
bouncing ball.  This was a very good test of the implementation.  I sent 
the module to the committee - I will try to find it if no one has it.

In any case, I used across signal flow to describe position, velocity 
and acceleration. The position was the integral of velocity with an 
initial position (the height above the ground).  The velocity was the 
integral of the acceleration with a DC initial condition which changes 
during transient (ic is dynamic).  The assert is set to 1 when the 
position is 0 (the ball hits the ground - I used "cross" for this) and 
the assert value (ic) is the negative of the velocity (the ball changes 
direction, thus bounces).

If assert is implemented correctly, the ball will bounce - if not, the 
balls distance will go negative and never return to the surface (a 
highly improbable example of Quantum tunneling).

PeterL