zpk function does not work

I am using MATLAB 2019b. The function zpk does not work (it is not identified). Can you please help?

[Stephan]

What shows up for

ver

[Mojtaba Bagheri]

MATLAB Version 9.7 (R2019b)

Signal Processing Toolbox Version 8.3 (R2019b)

Answer 1

[Star Strider]

Run these lines from your Command Window or a script:

restoredefaultpath 
rehash toolboxcache 

then try what you did before again.

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