What is the syntax problem?

c1*(c2/u[2]-c3*u[3]-c4)*exp(-c5/u[2])+c6*u[1]

someone can help me?

[Torsten]

Replace [ ] by ( )

[Antonio Itta]

[Antonio Itta]

doesn't work

[Torsten]

I don't know what Simulink requires. As MATLAB expression, it works for me.

Maybe the unnecessary bracket around u(3) must be deleted.

syms c1 c2 c3 c4 c5 c6
u = [2 4 6]

u = 1×3

2 4 6

c1*(c2/u(2)-c3*(u(3))-c4)*exp(-c5/u(2))+c6*u(1)

ans = 

[Star Strider]

If ‘u’ is supposed to be the unit step function, use heaviside or write your own, for example —

u = @(t) t>=0;

Also, it may be necessary to use element-wise operations. See: Array vs. Matrix Operations for details.

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