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From: | Mike Miller |
Subject: | [Octave-bug-tracker] [bug #56069] [octave forge] (symbolic) Laplace transform of sin(w*t) gives wrong value |
Date: | Thu, 4 Apr 2019 00:59:26 -0400 (EDT) |
User-agent: | Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36 |
Update of bug #56069 (project octave): Summary: Symbolic Laplace transform of sin(w*t) gives wrong value => [octave forge] (symbolic) Laplace transform of sin(w*t) gives wrong value _______________________________________________________ Follow-up Comment #1: It's nothing special about the variable 'w', but it's about the sorting order of the variables. When you pass an expression instead of a function as the first argument, the 'symvar' function is used to extract the variable that is closest to 'x'. I think this is a Matlab compatibility thing. @cbm is that right? So for the expressions 'sin(a*t)' and 'sin(b*t), 't' is chosen as the independent variable that the Laplace transform is computed over. But for 'sin(w*t)', 'w' is chosen instead of 't'. One example way to work around this is to define the expression as a function of t: >> f(t) = sin(w*t); >> laplace (f) ans = (sym) w ─────── 2 2 s + w _______________________________________________________ Reply to this item at: <https://savannah.gnu.org/bugs/?56069> _______________________________________________ Message sent via Savannah https://savannah.gnu.org/
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