Transfer function estimation
sys = tfest(data,np)
sys = tfest(data,np,nz)
sys = tfest(data,np,nz,iodelay)
sys = tfest(___,Name,Value)
sys = tfest(data,init_sys)
sys = tfest(___,opt)
estimates
a continuoustime transfer function, sys
= tfest(data
,np
)sys
,
using time or frequencydomain data, data
, and
contains np
poles. The number of zeros in the sys
is max(np1,0)
.
estimates
a transfer function containing sys
= tfest(data
,np
,nz
)nz
zeros.
estimates
a transfer function with transport delay for input/output pairs sys
= tfest(data
,np
,nz
,iodelay
)iodelay
.
uses
additional options specified by one or more sys
= tfest(___,Name,Value
)Name,Value
pair
arguments. All input arguments described for previous syntaxes also
apply here.
uses
the linear system sys
= tfest(data
,init_sys
)init_sys
to configure the initial
parameterization of sys
.
specifies
the estimation behavior using the option set sys
= tfest(___,opt
)opt
.
All input arguments described for previous syntaxes also apply here.

Estimation data. For time domain estimation, Timeseries models, which are models that contain no measured
inputs, cannot be estimated using For frequency domain estimation,
For multiexperiment data, the sample times and intersample behavior of all the experiments must match. 

Number of poles in the estimated transfer function.
For systems that are multipleinput, or multipleoutput, or both:


Number of zeros in the estimated transfer function.
For systems that are multipleinput, or multipleoutput, or both:
For a continuoustime model, estimated using discretetime data,
set For discretetime model estimation, specify 

Transport delay. For continuoustime systems, specify transport delays in the
time unit stored in the For a MIMO system with Ny outputs and Nu inputs,
set The specified values are treated as fixed delays.
Use 

Estimation options.


Linear system that configures the initial parameterization of You obtain If
If If 
Specify optional
commaseparated pairs of Name,Value
arguments. Name
is
the argument name and Value
is the corresponding value.
Name
must appear inside quotes. You can specify several name and value
pair arguments in any order as
Name1,Value1,...,NameN,ValueN
.

Sample time. Use the following values for Default: 

Input delay for each input channel, specified as a scalar value
or numeric vector. For continuoustime systems, specify input delays
in the time unit stored in the For a system with You can also set Default: 0 

Feedthrough for discretetime transfer function, specified as
an NybyNu logical matrix. Ny is
the number of outputs, and Nu is the number of
inputs. To use the same feedthrough for all inputoutput channels,
specify Consider a discretetime model with two poles and three zeros: $$H({z}^{1})=\frac{b0+b1{z}^{1}+b2{z}^{2}+b3{z}^{3}}{1+a1{z}^{1}+a2{z}^{2}}$$ When the model has direct feedthrough, Default: 

Identified transfer function, returned as an Information about the estimation results and options used is
stored in the
For more information on using 
[1] Garnier, H., M. Mensler, and A. Richard. “Continuoustime Model Identification From Sampled Data: Implementation Issues and Performance Evaluation.” International Journal of Control, 2003, Vol. 76, Issue 13, pp 1337–1357.
[2] Ljung, L. “Experiments With Identification of ContinuousTime Models.” Proceedings of the 15th IFAC Symposium on System Identification. 2009.
[3] Young, P. C. and A.J. Jakeman. “Refined instrumental variable methods of timeseries analysis: Part III, extensions.” International Journal of Control 31, 1980, pp 741–764.
[4] Drmac, Z., S. Gugercin, and C. Beattie. “Quadraturebased vector fitting for discretized H_{2} approximation.” SIAM Journal on Scientific Computing. Vol. 37, Numer 2, 2014, pp A625–A652.
[5] Ozdemir, A. A., and S. Gumussoy. “Transfer Function Estimation in System Identification Toolbox via Vector Fitting.” Proceedings of the 20th World Congress of the International Federation of Automatic Control. Toulouse, France, July 2017.
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