[scilab-Users] transfer function, z^-1 form

[Collette yann]

For me it corresponds to the good transfert function:

     0.31 + 0.38z                    z^2* (0.31*z^-2 + 0.38*z^-1)
   ----------------         =       ------------------------------------
   0.55 + 0.86z + z ^2            z^2*(0.55*z^-2 + 0.86z^-1 + 1)

Scilab seems to have simplified in a way your transfert function

YC


David PICARD a écrit :
> I need some help to define the following transfer function :
>
>  0.381417 z^-1 + 0.310306 z^-2
> ---------------------------------
> 1 - 0.857089 z^-1 + 0.548812 z^-2
>
> This is a 2nd order system : w0=1, Damp=1.3, Gain=1.0, Te=1s
>
> I tried :
> -->z=%z;
> -->sys=syslin(1.0,(0.38*z^-1+0.31*z^-2)/(1+0.86*z^-1+0.55*z^-2))
> sys  =
>
>      0.31 + 0.38z
>    ----------------
>                    2
>    0.55 + 0.86z + z
>
>
> But it NOT what I asked !!! Help !
>
> It is so straightforward with GNU Octave, that I am really frustrated !
>> sys=tf([0.000000 0.381417 0.310306],[1.000000 -0.857089 0.548812],1.0);
>> step(sys)   // shows the oscillating, stabilizing step response
>
>
>