ss2tf

Converts state-space model parameters to transfer function model parameters.

Syntax

[NUM, DEN] = ss2tf(A, B, C, D)

[NUM, DEN] = ss2tf(A, B, C, D, K)

Inputs

A
The state matrix (n x n), where n is the number of states.
B
The input matrix (n x p), where p is the number of inputs.
C
The output matrix (q x n), where q is the number of outputs.
D
The direct transmission matrix (q x p).
K (optional)
Scalar to extract results for input K. Default: 1.

Outputs

NUM
The numerator polynomial coefficient vector(s).
DEN
The denominator polynomial coefficient vector.

Examples

SISO case:
sys_tf = tf([1],[1 3 4]);
sys = ss(sys_tf);
[tf_num,tf_den] = ss2tf(sys.a,sys.b,sys.c,sys.d)
num = [Matrix] 1 x 2
4.44089e-16  1.00000e+00
den = [Matrix] 1 x 3
1.00000  3.00000  4.00000
MIMO case with two outputs and three inputs, selecting input 2:
A = [0.9,0,0.6,-1.4,-4.2;
0.2,0.1,-0.2,0.5,0.6;
-4.3,0,2.2,0,2.4;
-3.7,-0.5,2.4,-0.6,2.7;
6.4,0.1,-4,-0.5,-4];

B = [-0.1,-0.1,0;
0,0,0.1;
-0.1,0.2,-0.1;
0.2,0.2,-0.6;
0.2,-0.1,0.1];

C = [2,7,-2,5,1;
0,-1,3,0,2];

D = [1,0,0;
0,0,0];

[num, den] = ss2tf(A, B, C, D, 2)
num = [Matrix] 2 x 5
0.30000  0.52000  8.02400  14.23650   3.95450
0.40000  0.19000  9.73500   5.46010  -0.09758
den = [Matrix] 1 x 6
1.00000  1.40000  25.39000  35.10400  15.45680  -0.62960