Transform a model to state-space form.
Syntax
[A,B,C,D,K,X0] = th2ss(th)
[A,B,C,D,K,X0,dA,dB,dC,dD,dK,dX0] = th2ss(th)
Description
th is the model given in the theta format. A, B, C, D,K, and X0 are the matrices in the state-space description
where 
is 
or 
depending on whether th is a continuous or discrete-time model.
dA, dB, dC, dD, dK, and dX0 are the standard deviations of the state-space matrices.
If the underlying model itself is a state-space model, the matrices correspond to the same basis. If the underlying model is an input-output model, an observer canonical form representation is obtained.
Algorithm
The computation of the standard deviations in the input-output case assumes that an A polynomial is not used together with a F or D polynomial in (7.2). For the computation of standard deviations in the case that the state-space parameters are complicated functions of the parameters, Gauss approximation formula is used together with numerical derivatives. The step sizes for this differentiation are determined by nuderst.
See Also
mf2th, ms2th, nuderst
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