Why does c2d function not work on a system defined using transfer function approach in the Control System Toolbox 6.2.1 (R14SP3)?

When I use a transfer function as an input argument to c2d function, I get the following error:

analy=tf([1],[1 1])

[digit, M]=c2d(analy,0.1,'tustin')

gives the following error:

 Transfer function:

   1

 -----

 s + 1

 ??? Error using ==> tf.c2d

 Too many output arguments.

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 2006b (R2006b). For previous product releases, read below for any possible workarounds:

The Control System Toolbox 6.2.1(R14SP3) documentation for the c2d function does not expliictly state the system format to be passed to this function.

The following syntax of this function:

[sysD, G]=c2d(sys, Tf, 'tustin')

assumes that 'sys' is a state-space model.