zpk function is missing

I am using MATLAB R2020b, and Signal processing toolbox Ver. 8.5. The "zpk" function does not work. I have already tried following recommendation but no success:

restoredefaultpath

rehash toolboxcache

Please help me.

[Fangjun Jiang]

There is no zpk() function in Signal Processing Toolbox Ver 8.5. What is the error of zpk() in R2020b if you have the Control System Toolbox?

Answer 1

[Fangjun Jiang]

I believe zpk() requires Control System Toolbox. Check to see if you have it

ver control

[Arash Kohli]

Thank you. I have installed it.

[taeho kim]

omg thank you so much

Answer 2

[Star Strider]

In the Signal Processing Toolbox, the [z,p,k] output is optional for several filter design functions. Use those with (for example) zp2sos or others to design the filter to be used with filtfilt to filter a signal.

[Arash Kohli]

Thank you,

I have to add some parts to an existing program which is using zpk. Is there any toolbox in which the zpk is included?

[Star Strider]

There are sevral. One zpk is in the Control System Toolbox, another zpk (introduced in R2014a) is in the Signal Processing Toolbox. (There are others as well, however I do not have those Toolboxes.)

Choose the one that works in the context of what you are doing.

Answer 3

[Ahmed Redissi]

Hi,

While there is no "zpk" function in the Signal Processing Toolbox, there is a method called "zpk" of the object "digitalFilter". If you have the Signal Processing Toolbox, you can call the "zpk" function if the input is a digitalFilter object. Here's an example:

hpFilt = designfilt('highpassiir','FilterOrder',8, ...
         'PassbandFrequency',75e3,'PassbandRipple',0.2, ...
         'SampleRate',200e3);
[z,p,k] = zpk(hpFilt);

You can learn more about it here:

https://www.mathworks.com/help/signal/ref/zpk.html