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ss2tf

ss2tf — conversion from state-space to transfer function

Calling sequence

[h]=ss2tf(sl)   
[Ds,NUM,chi]=ss2tf(sl)  

[h]=ss2tf(sl,"b")   
[Ds,NUM,chi]=ss2tf(sl,"b")  


[h]=ss2tf(sl,rmax)   
[Ds,NUM,chi]=ss2tf(sl,rmax)

Parameters

sl : linear system (syslin list)
h : transfer matrix

Description

Called with three outputs [Ds,NUM,chi]=ss2tf(sl) returns the numerator polynomial matrix NUM, the characteristic polynomial chi and the polynomial part Ds separately i.e.:



h=NUM/chi + Ds

Method:

One uses the characteristic polynomial and det(A+Eij)=det(A)+C(i,j) where C is the adjugate matrix of A.

With rmax or "b" argument uses a block diagonalization of sl.A matrix and applies "Leverrier" algorithm on blocks. If given, rmax controls the conditionning (see bdiag).

Examples



s=poly(0,'s');
h=[1,1/s;1/(s^2+1),s/(s^2-2)]
sl=tf2ss(h);
h=clean(ss2tf(sl))
[Ds,NUM,chi]=ss2tf(sl)

See also

tf2ss, syslin, nlev, glever
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