inverse transform returns 'variable undefined

[ptc-1716002]

Attempting to perform an inverse Laplace transform
on a simple 2nd order polynomial (2 poles, 1 zero)

The symbolic operation works, but when I attempt to
assign the result to a function, Mathcad 12.1 always
returns "This variable is undefined".

Suggestions anyone?

[RichardJ]

It appears to be a bug in version 12. It works fine in versions 11, 13 and 14. I can't actually check it in version 12 though because it's such a lemon version of Mathcad last time I changed PC I couldn't be bothered to install it along with all the others. Perhaps someone else that has version 12 installed can check.

Richard

[AlvaroDíaz]

On 2/16/2010 3:57:16 PM, rijackson wrote:
>It appears to be a bug in version 12.

Without version 12 I guess that the bug is in the t variable: try to add ",t" in the inverse laplace. Also, write t:=t after t:=0.

If not, must to manual assign the impulse function by copy & paste.

Regards. Alvaro.

[mzeftel]

I recommend that you upgrade to Mathcad 14, which you can do for only $99 including all extension packs and libraries at http://www.ptc.com/go/mathcad99.

Mona

[StuartBruff]

On 2/17/2010 10:33:47 AM, MonaZ wrote:
== I recommend that you upgrade to Mathcad 14, which you can do for only $99 including all extension packs and libraries at http://www.ptc.com/go/mathcad99.

And, as someone with no commercial interest in Mathcad, I think that's pretty good advice. M14 is significantly better than M12.

Stuart

[alnstevens]

Mathcad 12 doesn't seem to like vectors in its inverse laplace transform! Replace by scalars and it works ok - see attached.

stv