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# I want convert laplace function into partial fractions like k1/(s+s1) + k2/(s+s2)

I have a expression in 's' domain: I(s)= Ip.(s-A)/(s^2+Bs+C) I want to convert to partial fractions like: I(s)= k1/(s-s1) + k2/(s-s2) and finally use in time domain as: i(t)=k1.exp(s1.t-t0) + k2.exp(s2t-t0) thank you for your attention

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Welcome to Ask Sage! Thank you for your question!

( 2018-04-17 17:56:29 +0100 )edit

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Is this what you want?

sage: var('s')
s
sage: var('t')
t
sage: L = (s-3)/(s^2-3*s+2)
sage: L.partial_fraction()
2/(s - 1) - 1/(s - 2)
sage: L.inverse_laplace(s,t)
-e^(2*t) + 2*e^t
sage: L.partial_fraction().inverse_laplace(s,t)
-e^(2*t) + 2*e^t


Once you have an expression like L = (s-3)/(s^2-3*s+2), if you type L.<TAB>, it will produce a list of all of the available methods. In this case there are a lot of possibilities, but inverse_laplace and partial_fraction are two of them. (If you can guess that something like partial_fraction might be there, you can also type L.p<TAB> or L.pa<TAB> to get a much shorter list.) You can also evaluate L.inverse_laplace? to get documentation.

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Asked: 2018-04-17 17:17:39 +0100

Seen: 92 times

Last updated: Apr 17 '18