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## Re: Signal library problem

 From: Nicholas Jankowski Subject: Re: Signal library problem Date: Thu, 23 May 2019 13:18:18 -0400

> A=[1 1 0; 1 -1 0; 0 0 -2];
>
> B=[2; 1; 1];
>
> C=[1 0 1];
>
> D=[0];
>
> ---Using matlab the result is this:
>
> >> [ num , den ] = ss2tf( A, B, C, D )
>
> num =
>
>      0     1     2     0
>
>
> den =
>
>      1     1    -2     0
>
>
> ---Using octave the result is:
>
> [ num , den ] = ss2tf( A, B, C, D )
> num =  1
> den =
>
>    1  -1
>
>

I do not get the same result as you.
Using Octave 5.1.0 on Windows 10, signal v1.4.1, control 3.2.0

>> A = [1 1 0; 1 -1 0; 0   0 2], B = [2;1;1], C = [1 0  1], D = [0]
A =
1   1   0
1  -1   0
0   0   2
B =
2
1
1
C =
1   0   1
D = 0
>> [num,den]=ss2tf(A,B,C,D)
num =
3.0000  -1.0000  -8.0000
den =
1.0000  -2.0000  -2.0000   4.0000

and in Matlab 2018b:

>> A = [1 1 0; 1 -1 0; 0   0 2], B = [2;1;1], C = [1 0  1], D = [0]
A =
1     1     0
1    -1     0
0     0     2
B =
2
1
1
C =
1     0     1
D =
0
>> [num,den]=ss2tf(A,B,C,D)
num =
0    3.0000   -1.0000   -8.0000
den =
1.0000   -2.0000   -2.0000    4.0000

other than the extra zero in the numerator (is that a significant compatibility bug?) these answers seem equivalent.