How can i use sign function under a function block in simulink ?

Hey guys, i'm new in using simulink. And i have a problem by using "sign(signum)" fucntion, in a fucntion block. When i write my formula inside the function block and run it. I have syntax error. But i'm pretty sure i wrote the formula correct. And when i remove sign function from the formula, it works(but not correctly). So how can i use this "sign" fucntion inside a function block ? Please help me i'm stuck in a project right now. Thank you

[Azzi Abdelmalek]

What syntax error?

[Mustafa]

/matlabcentral/answers/uploaded_files/11756/Capture.JPG The only reason why i got error is "sign" function. Because when i removed it from the equation, it works. And i dont know where i make mistake

Answer 1

[A Jenkins]

Is that the full equation? Your parentheses don't match. (7 open and only 6 close)

Perhaps should be

(-Kc*u(1)-Bc*u(4)+Kc*u(2)/N-Fc*sign(u(5)+u(9)))/Jcin

[Mustafa]

Thank you very much.I made the correction, but still i got syntax error in the same function block :/

[A Jenkins]

Check that all of your parameters, Kc, Bc, etc are defined.

Also check that your input signal u, has a width of at least 9.

Answer 2

[Luuk Ladegaard]

Hey, I don't know whether you're still struggling with this problem, but I discovered that for some reason, you need to use "sgn()" instead of "sign()". I have no idea what's up with that, it's not an existing Matlab function, but it works in Simulink. I guess it's a mistake. :/

[Zhe Chen]

I have the same problem. And your method works.

I dont know either why is that when I changed the sign function to sgn, the syntax error goes away.