Why do I receive an error when specifying the frequency range argument in FFPLOT in the System Identification Toolbox 6.1 (R14SP1)?

I am using the FFPLOT (or BODE) function. When I call it with a frequency range argument as specified in the following documentation:

web([docroot,'/toolbox/ident/bode.html#978467'])

wmin = 0; wmax = 0.5; NP = 100; w = {wmin,wmax,NP};

[mag, phase] = bode(mfb,w)

I receive the following error:

 ??? Error using ==> ffplot

 Error using ==> bodeaux

 When BODE or FFPLOT is called with output argument the syntax is

[MAG,PHASE] = BODE(Model,W) with W a vector of reals

or [MAG,PHASE,W,SDMAG,SDPHASE] = BODE(Model).

 Error in ==> show_ffplot_bug at 32

 [mag, phase] = ffplot(mfb,w)

When I make the call to FFPLOT without output arguments, the above format works, but I need to use output arguments.

Answer 1

[MathWorks Support Team]

This change has been incorporated into the documentation in Release 14 Service Pack 3 (R14SP3). For previous releases, read below for any additional information:

This has been verified as an error within the documentation for the System Identification Toolbox for the BODE function. When calling BODE or FFPLOT with output arguments, you must pass the frequency range data as a vector of real numbers in the form of w = [wmin:stepsize:wmax].

If you are not using output arguments, the format from the documentation:

w = {wmin,wmax,NP}

will work.