# system of differential equations

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Seba 2011년 6월 6일
댓글: ikhlas 2023년 11월 3일
Hello All,
I am wondering how to solve system of differential equations using simulink?
plz do help me how to make a simulink model.
regards,

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### 답변 (7개)

Titus Edelhofer 2011년 6월 6일
Hi,
you could open the vdp model as a typical second order differential equation. The way to go stays the same when you have a system: put as many integrators per row of your system as you have orders of differentiation, and feed them with the variables that make up the differential equation.
Titus
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Arnaud Miege 2011년 6월 6일
Write down the equations on paper and then implement them using the various blocks available in Simulink. A tip: it's generally better to start with the highest order derivative and integrate rather than the other way round and differentiates. Have a look at Modeling Best Practises in the Simulink documentation and also at the interactive tutorials on the MathWorks web site.
HTH,
Arnaud
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Seba 2011년 7월 14일
is it possible to find solution of this system with simulink:
x''(t)+ x'(t)+ z''(t) = 0
x(t)+ x'(t)+ z'(t) + 1 = 0
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Arnaud Miege 2011년 7월 14일
That system does not have a solution. If you differentiate the second equation once more, you have:
x'' = -x' - z''
z'' = -1 - x'' - x'
If you then substitute the expression for z'' in the second equation into the first, you get:
x'' = -x' + 1 + x'' + x'
in other words, 1 = 0.
I suggest you check these equations, they're probably wrong.
ikhlas 2023년 11월 3일
how can I solve this system using Euler's method in matlab
u'=p
v'=q
p'=0
q'=0
such that u(0)=0 , v(0)=0, p(0)=0, q(0)=1?

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Seba 2011년 7월 15일
here is a system of equations. Is it possible to find solution of this system with Simulink ?
Id, Iq,Ia,Ib,w,Me are unknown functions, Ud an Uq are known functions, other are constants
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Arnaud Miege 2011년 7월 15일
Yes, as long there is a solution, you can represent any system of ODEs in Simulink. Start working out the higher order derivatives and use integrator blocks to work your way up. Read the documentation, e.g.:

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Seba 2011년 7월 19일
do you have any examples on how to solve equations with complex numbers in Simulink?
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Seba 2011년 7월 21일
how can I solve equations with real-valued signals with simulink, do you have any documentation on that?
Arnaud Miege 2011년 7월 21일
Like I said before (read my previous answers/comments), you can represent any system of ODEs in Simulink. Start working out the higher order derivatives and use integrator blocks to work your way up. Read the documentation, e.g.:
Also work through the tutorials I suggested and look at Modelling Best Practises in the documentation.

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Seba 2011년 7월 21일
I don't understand why the first example doesn't work and second example works
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Walter Roberson 2011년 7월 21일
Hmmm?
>> 10+10i
ans =
10 + 10i
Arnaud Miege 2011년 7월 22일
OK, fair enough.

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Seba 2011년 7월 25일
I have tried with delay block but i can't get the solution of the equation(which is -2.5-2.5*i)??
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Seba 2011년 7월 26일
what is a math block? Is that a block in Simulink?
Walter Roberson 2011년 7월 26일

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