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Asked by Rajesh
on 26 May 2013

I'm trying to simulate a first order ODE(involving column vector) in simulink. I've written the code for differential equation in matlab files which gives the correct result.But when the same equation represented in simulink doesn't give the correct output.

So i want to know why the simulink model is behaving weirdly or i'm missing some options with simulink or its a bug with simulink.

I'm giving the links for the model and code here. # timeresponse.m http://pastebin.com/X66MV00n # dof3.m http://pastebin.com/kQhk1ab1 # new3dof.slx https://www.box.com/s/pa7dm0edj8r6ngg5wb0d #

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Answer by Azzi Abdelmalek
on 26 May 2013

Edited by Azzi Abdelmalek
on 29 May 2013

Accepted answer

The matrices in your simulink model are different from your script, in your simulink model set

**Edit** regarding to Jan's remarks

the first matrix to Mat1

Mat1=Mass\M1

the second matrix to Mat2

Mat2=Mass\M2

Also, in your scope parameters, uncheck **limit data points to last** under **history**

Also, add a gain block with value set to 180/pi to one of your first output

Jan Simon
on 26 May 2013

"inv(Mass) * M1" hurts the eyes, when one remembers, that "Mass\M1" is faster and more stable.

Rajesh
on 27 May 2013

Thanks for the answer, Mr.Abdelmalek . I corrected my matrix values (sorry for a silly mistake on my part). But still the graphs don't agree.Can you please point me where i'm doing it wrong?

Here's the link for updated version... https://www.box.com/s/pa7dm0edj8r6ngg5wb0d

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