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I am taking a Control Systems class as part of my electrical engineering degree. I have to do some Laplace Transforms regularly so I would like to be able to take the Laplace Transform of a time domain function, but my calculator is really pissing me off.

I am trying to do this in CAS mode (by pusing CAS button). I normally use RPN mode in HOME. But some things seems to be less troublesome if I use CAS mode so that is the mode I am in when trying this stuff. If I type this:

laplace(exp(t)*Sin(t),t,s) the calculator says "undef".

I am not typing in "laplace" I am using the toolbox -> Calculus-> Transform->Laplace. I do not have any user variables defined as 's' or 't'. If I type purge(s,t) the calculator returns ["no such variable s" "no such variable t"].

I have read the manual. On page 370 it shows the following for Laplace Transform:

laplace(exp(x)*sin(x)) gives 1/(x^2-2*x+2)

If I type that the calculator gives me an error stating "undef"

Can someone please help me figure this out? This should be pretty straightforward but it's not going well for me. I am thinking it has something to do with the variables chosen or even capitalization or maybe my CAS settings.

Please help me. I'm dying here.

Check that t,s,x are free variables, purge(t,s,x) if needed. After that laplace(exp(t)*sin(t),t,s) should work.