Transfer function with symbol

Hello everyone.... I'm trying to create a transfer function with a symbol like follow...

syms K

s = tf('s');

control = K*(s+1)/(s+15);

but matlab doesn't seem to like this cuz i get an error like....

??? Error using ==> sym.sym Conversion to 'sym' from 'tf' is not possible.

Error in ==> sym.mtimes at 9 B = sym(B);

any ideas?

Thanks!

Answer 1

[Wayne King]

s = tf('s');

Creates an object of class tf. tf() is not an overloaded method in the Symbolic Toolbox.

Define your K as a constant.

K = 3;
cntrl = K*(s+1)/(s+15);

[Peter]

Thanks for the reply!

But is there anyway to leave K as K?

[Victor Gruner]

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