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Inverse Laplace Transform and Absolute Value

Forum|Forum|4 months ago
November 18, 2025
2 replies
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Currently using MathCAD v15 (M050). I have Prime 10 but am having licensing issues at the moment.

Anyway, I'm having trouble understanding why the invlaplace function won't evaluate as shown in the attachment. If I remove the absolute value sign, then it all works as expected (am I just running up against a domain issue and need to use the "assume" keyword.....or something......?)

Any advice is welcomed and appreciated! If Prime 10 has no problem with it, then that's my answer (just gotta lean on IT to get the license issues sorted).

Thanks!

Electrical_Engineering

Best answer by Werner_E

In Mathematics the absolute function is kind of a beast which usually is quite hard to handle.

Much more difficult like a simple function like the squaring

or even the Heaviside function

(we see "1" instead of "Phi(t)" because the result of course is valid only for t>=0).

We could try to rewrite the absolute value using the modulo function, but unfortunately the laplace operator can't deal with the modulo function

25-Diamond I

Looks like what you demand is too hard for the symbolics in Mathcad.

Its also too hard for Prime's symbolics:

And Wolfram Alpha isn't able to come up with the desired result |sin(t)| either:

Answer

25-Diamond I

In Mathematics the absolute function is kind of a beast which usually is quite hard to handle.

Much more difficult like a simple function like the squaring

or even the Heaviside function

(we see "1" instead of "Phi(t)" because the result of course is valid only for t>=0).

We could try to rewrite the absolute value using the modulo function, but unfortunately the laplace operator can't deal with the modulo function

Author

3-Newcomer

Thank you for the response!

21-Topaz I

t.t.