Error with freqz plot

Hello, I am trying to see the frequency plot of the filter but it is showing error as

The Numerator and denominator of the transfr frunstion must be stored in vectors at this line freqz(sos1,1001);

Fs = 100;
Fn = Fs/2;
% Design First Filter: 
Ws1 = [0.2  0.35]/Fn;
n1 = 2;                             % Filter ORder
R = 20;                             % Stopband Attenuation
[b1, a1] = cheby2(n1,R,Ws1,'stop'); % Create Filter
[sos1,g1] = tf2sos(b1,a1);          % SOS Implementation
figure(5)
freqz(sos1,1001)                    % Plot Normalised Response

Can anyone explain why is the error showing up. thanks.

[Star Strider]

No idea. I just ran that code again (I tested it before I posted it) and it ran without errors (R2014a).

[BHASKER GURRAM]

i am also facing same problem

Answer 1

[Honglei Chen]

If I remember correctly you have an older version of MATLAB which does not support this syntax. You could try the following instead

freqz(b1,a1,1001)

For a 2nd order filter, they should be pretty much the same.

HTH