inverse laplace of s certain function

hello. I am trying to find the inverse laplace of a function such as exp(-3s)^2/(s-4) which I know the answer will have a unit step which is the Heaviside but unfortunately it is outputting me the same what I typed;ilaplace(f).Any ideas how to get the answer?

Answer 1

[Star Strider]

It works for me in R2017b:

syms s t 
F = exp(-3*s)^2/(s-4);
f = ilaplace(F,s,t)

f =
heaviside(t - 6)*exp(4*t - 24)

[Marwan Malaeb]

So I need to update the version. Thanks bro

[Star Strider]

My pleasure.

[Marwan Malaeb]

Try this please (1-exp(3s))^2/(s-4)

[Star Strider]

I get:

f =
exp(4*t) - 2*ilaplace(exp(3*s)/(s - 4), s, t) + ilaplace(exp(6*s)/(s - 4), s, t)

FWIW, WolframAlpha (link) can’t invert it either (as: invlaplace( (1-exp(3*s))^2/(s-4) )).