Is there a block in Simulink to load equations in state variables ?

I remember having seen some time ago a custom block in Simulink, that allowed to place a system of equations written in the format of state variables (in several lines). I haven't found it again and I don't see it in the repositories. I would be very grateful if someone could tell me about it.

My best regards.

Answer 1

[Paul]

This one?

State Space

[Paul]

One can enter user defined differential equations in a Matlab Function block. The body of the function would look like:

function xdot = pendulum(x)
g = -9.81;
L = 1;

xdot(1) = x(2);
xdot(2) = -g/L*sin(x(1));

end

Mabe this is what you're looking for?

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Answer 2

[Roberto Carabajal]

No, it was something like

x(1)= .........

x(2)= .......

x(3)= ........

where x(n) means derivative of x(n-1)

x(1) means x dot.

Each x() is placed in one line in the box

[Paul]

Now I'm confused about what the equations are that need to be implemented. Can you write a few lines of Matlab code that illustrates an example set of equations?

Answer 3

[Roberto Carabajal]

Suppose the sinple pendulum differential equation:

ẋ1=x2

ẋ2= -g/l*sin(x1)