why matlab 2019a, 2016a doesnt recognize modalfrf?

When I try modelfrf I got this responce;

Undefined function or variable 'modelfrf'.

How can I solve this problem

Answer 1

[Steven Lord]

This function was introduced in Signal Processing Toolbox in release R2017a.

Your installation of release R2016a is too old to contain that function even if it has Signal Processing Toolbox installed.

Your installation of release R2019a is new enough to contain that function but likely does not have Signal Processing Toolbox installed.