@Preben Alsholm 

I think the end conclusion is this: It's a good idea to set up the system of ODE's using function notation and let Maple do its solution. This way, you do not have to program details of how the solution functions are found.  This has applicability for systems of "state space" equations typical of dynamic systems.

But when it comes times to insert parameters (mass, damping, stiffness in the state space case), it seems that the solutions are perfectly well expressed and accessible (for plotting, etc.) by grouping them into a list. Individual elements of the list (the solutions) can then be drawn out as expressions.

@Preben Alsholm 

Very effective, and I've reproduced the solution & plot, thanks!

Sorry, as a "casual user", I'm not used to the reasoning behind the 5 steps leading up to the plots. (allvalues, evalc, evalf). Is it possible to give a hint as to why these steps are needed in that order, so that I can pass that along to the students? (yep, I'm a teacher...)

By the time we get to the variables res, RES, and Z, are these functions or expressions?  When I see the argument for "t" in plot, I'm thinking this looks like a group (list?) of expressions, not functions....

Thanks!

robert w.

Thank you for your answer.  Yes, this is a stress or strain matrix, hence symmetric and real.

I understood the importance of telling Maple that shape=symmetric; otherwise, even a symmetric real

matrix comes up with complex eigenvalues (albeit with very small complex parts).

What I didn't appreciate was the importance of what you said--making this a matrix of "floats".

This was made clear by the attached. 

Download MAE505&CIE511_ex_15_.mw

This forces the eigen-stuff to be normalized & well-behaved.

Thanks for the comment! 

robert

Thank you for your answer.  Yes, this is a stress or strain matrix, hence symmetric and real.

I understood the importance of telling Maple that shape=symmetric; otherwise, even a symmetric real

matrix comes up with complex eigenvalues (albeit with very small complex parts).

What I didn't appreciate was the importance of what you said--making this a matrix of "floats".

This was made clear by the attached. 

Download MAE505&CIE511_ex_15_.mw

This forces the eigen-stuff to be normalized & well-behaved.

Thanks for the comment! 

robert