Laplace Transform gives "undef" in CAS mode

02012018, 03:07 AM
Post: #1




Laplace Transform gives "undef" in CAS mode
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^22*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. 

02012018, 06:49 AM
Post: #2




RE: Laplace Transform gives "undef" in CAS mode
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.


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