Extract continuoustime linear statespace model around operating point
argout
= linmod('sys
');argout
= linmod('sys
', x, u);argout
= linmod('', x, u, para);
sys
argout
= linmod('sys
', x, u, 'v5');argout
= linmod('sys
', x, u, para, 'v5');argout
= linmod('sys
', x, u, para, xpert, upert, 'v5');
 Name of the Simulink^{®} system from which the linear model is extracted. 
State ( x = Simulink.BlockDiagram.getInitialState('sys'); You
can then change the operating point values within this structure by
editing If the state
contains different data types (for example,  
 Sample time of the discretetime linearized model 
 An optional argument that invokes the perturbation algorithm
created prior to MATLAB^{®} 5.3. Invoking this optional argument
is equivalent to calling 
 A threeelement vector of optional arguments:

 The perturbation values used to perform the perturbation of all the states and inputs of the model. The default values are xpert = para(1) + 1e3*para(1)*abs(x) upert = para(1) + 1e3*para(1)*abs(u) When a model has model references using the Model block, you must use the Simulink structure
format to specify xpert = Simulink.BlockDiagram.getInitialState('sys'); You
can then change the perturbation values within this structure by editing The
perturbation input arguments are only available when invoking the
perturbation algorithm created prior to MATLAB 5.3, either by
calling 

linmod and dlinmod both
also return a transfer function and MATLAB data structure representations
of the linearized system, depending on how you specify the output
(lefthand) side of the equation. Using linmod as
an example:

linmod
compute a linear statespace model
by linearizing each block in a model individually.
linmod
obtains linear models from systems
of ordinary differential equations described as Simulink models.
Inputs and outputs are denoted in Simulink block diagrams using
Inport and Outport blocks.
The default algorithm uses preprogrammed analytic block Jacobians for most blocks which should result in more accurate linearization than numerical perturbation of block inputs and states. A list of blocks that have preprogrammed analytic Jacobians is available in the Simulink Control Design™ documentation along with a discussion of the blockbyblock analytic algorithm for linearization.
The default algorithm also allows for special treatment of problematic blocks such as the Transport Delay and the Quantizer. See the mask dialog of these blocks for more information and options.
By default, the system time is set to zero. For systems that
are dependent on time, you can set the variable para
to
a twoelement vector, where the second element is used to set the
value of t
at which to obtain the linear model.
The ordering of the states from the nonlinear model to the linear model is maintained. For Simulink systems, a character vector variable that contains the block name associated with each state can be obtained using
[sizes,x0,xstring] = sys
where xstring
is a vector of strings whose ith
row is the block name associated with the i
th state.
Inputs and outputs are numbered sequentially on the diagram.
For singleinput multioutput systems, you
can convert to transfer function form using the routine ss2tf
or
to zeropole form using ss2zp
. You can also convert
the linearized models to LTI objects using ss
.
This function produces an LTI object in statespace form that can
be further converted to transfer function or zeropolegain form using tf
or zpk
.
The default algorithms in linmod
handle Transport
Delay blocks by replacing the linearization of the blocks with a Pade
approximation. For the 'v5'
algorithm, linearization
of a model that contains Derivative or Transport Delay blocks can
be troublesome. For more information, see Linearizing Models.