MATLAB: Why matlab 2019a, 2016a doesnt recognize modalfrf

modelfrf

When I try modelfrf I got this responce;

Undefined function or variable 'modelfrf'.

How can I solve this problem

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.

This is expected behavior because the MODALFRF function is introduced in R2017a.

I suggest you to upgrade to R2017a version or later to access the MODALFRF function.

For more information on the above function:

As an workaround in R2015a to get the frequency response function you can use the FFT function:

>> FRF = fft(output)./fft(input);