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Topic: Using piecewise-constant functions in ode Simulink
Replies: 1   Last Post: Feb 23, 2013 11:58 PM

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 Phil Goddard Posts: 358 Registered: 1/27/12
Re: Using piecewise-constant functions in ode Simulink
Posted: Feb 23, 2013 11:58 PM

> I want to integrate the multiplication of a cosine with a
> piecewise-constant function (e.g. 1 from 0 to 1/1000, -1 from 1/1000 to
> 2/1000, ...)

Why don't you use a square wave that changes from 1 to -1 and back every thousandths of a second?

> y at t=3/1000 should be 8.00487e-4 if I solve analytically but Simulink
> has 8.29766161000261e-4 :( :(

That's not really a meaningful comparison.
Simulink is, by its nature, an approximation, and its accuracy depends not just on the problem, but also the solver and the solver parameters being used.

Phil.

Date Subject Author
2/23/13 Peter Mairhofer
2/23/13 Phil Goddard