Why does LIMITCYCLE function not work with DFILT objects in Signal Processing Toolbox 6.2 (R14)?

I am designing fixed-point filters with the Filter Design Toolbox 3.0 (R14), and the LIMITCYCLE function does not work for the DFILT objects that I am supposed to be using with the Filter Design Toolbox 3.0 (R14). I tried using it with a DFILT.DF2SOS object and received the following error:

 ??? Function 'limitcycle' is not defined for values of class 'dfilt.df2sos'.

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 14 Service Pack 3 (R14SP3). For previous product releases, read below for any possible workarounds:

The ability to use the LIMITCYCLE function with the DFILT objects is not available in Signal Processing Toolbox 6.2 (R14).

To work around this issue, try to design your filter using QFILT objects which can be used with LIMITCYCLE function.