how to resolve Transfer function error?

When I am using trasnfer function command tf, I am always getting an error "Undefined function 'tf' for input arguments of type 'double'."? I am unable to resolve it.

Answer 1

[madhan ravi]

That function requires Control System Toolbox and a valid license for it.

[lounis chehrit]

Hello,

I hope you're doing well.

I have an issue, can you help me on this please?

I have two signal column vectors ( input and output ) : ( very large but they both have the same size):

x_inp=[0.0001, -0.0233, ..... ]

x_out=[0.005, -0.0053, ..... ]

i also have a system TF, which is represented like this:

Real( H(s) ) = 23 cos (2*pi*s) + 12 cos (5*pi*s/10) + 1 cos (2*pi*s)/19 + 0.75 cos (5*pi*s/10).

Imag( H(s) ) =11 sin (3*pi*s) + 7 cos (9*pi*vs2) + 10 sin (2*pi*s)/2 + 1.25 sin (4*pi*s/18).

I want to know if , TF( x_out / x_inp ) = H(s).

I tried this :

sys = Real( H(s) ) + i.* Imag (H(s) ).

so to compute the TF( x_out / x_inp ) i did this :

TL1 = tf ( x_inp )

TL2 = tf ( x_out).

and then :

signal = TL2 ./ TL1.

But it doesn't work.

Can anyone please, tell me how can i compute that tf and compare them to the H(s) system.

Or is there another method to see if TF( x_out / x_inp ) = H(s) ? Wether fft method or something like that.

Thank you in advance !