lost access to tf and ss from id toolbox

Hello,

I seem to have lost access to tf and ss (at least) from the sysident toolbox at the command line. If I type ss or tf at the command line (with arguments that worked fine last week) I get:

Undefined function 'ss' for input arguments of type 'double'.

Undefined function 'tf' for input arguments of type 'double'.

Undefined function or variable 'tf'.

Undefined function or variable 'ss'.

but which tf and which ss return the correct locations

/data_1/local/MATLAB/R2012b/toolbox/ident/ident/@idParametric/ss.m

but I can start the ident gui and have it create a statespace or transfer function model.

The sys admin said he changed a backup disk in the machine, but not the disk that matlab was installed on. I tried to rehash but that didn't change anything. I've restarted, removed my additional path stuff from startup.m etc all to no avail.

Any ideas?

Thank you

Jason

Answer 1

[Rajiv Singh]

It seems Control System Toolbox is not available to you anymore. What do you get when you type "ver control" in MATLAB?

Answer 2

[Jason]

Rajiv,

We do not have the control system toolbox, only the system identification toolbox: System Identification Toolbox Version 8.1 (R2012b)

The required functions are in the ident toolbox directory, e.g.

/MATLAB/R2012b/toolbox/ident/ident/@idParametric/ss.m

We have never had the control toolbox, has something changed?

Thank you

[Rajiv Singh]

TF, SS are model objects that belong to Control System Toolbox. What you see under ident/ident/@idParametric are converter functions that share the same name with the object constructors. Thus ss(sys_id_model) converts the identified model sys_id_model into SS object of Control System Toolbox. Of course, the conversion only works if you have Control System Toolbox installed.