SparseModalTruncationOptions
Description
This object contains model order reduction options of sparse linear time-invariant
models, and is contained in the Options
property of a
SparseModalTruncation
object R
created using reducespec
. To
configure these options, use dot notation, for example, R.Options.ModeOnly =
true
.
For the full workflow, see Task-Based Model Order Reduction Workflow.
Properties
Focus
— Frequency range of interest
[0 inf]
(default) | vector
Frequency range of interest, specified as a vector of form
[fmin,fmax]
. When you specify a value for this property, the
algorithm computes only modes in this frequency range.
By default, the focus is unspecified ([0 inf]
) and the algorithm
computes the MaxOrder
modes with smallest magnitude.
MaxOrder
— Maximum order of modal approximation
1000
(default) | positive integer
Maximum order of the modal approximation, specified as a positive integer. This value limits the number of eigenvalues computed by the Krylov-Schur iterations and the order of the modal approximation of the original sparse model.
ModeOnly
— Flag to only compute modes
false
or 0
(default) | true
or 1
Flag to only compute modes for the original system sys
, specified
as a logical 0
(false
) or 1
(true
).
When
R.Options.ModeOnly
istrue
, the software computes only the pole locations, damping, and natural frequency of the poles, which correspond to theMode
,Damping
, andFrequency
properties ofR
, respectively.When
R.Options.ModeOnly
isfalse
, the software computes a full modal decomposition and populates all properties ofR
.
DCFrequency
— Frequency for evaluating DC contributions
0
(default) | nonnegative scalar
Frequency for evaluating and matching DC contributions, specified as a nonnegative scalar.
For models with integrators, you cannot evaluate modal contributions at DC since the DC gain is infinite. To evaluate modal contributions and match gains at a different frequency, set the property to a positive value. The default value of this property corresponds to the DC contributions.
InputScaling
— Input scaling factors
[]
(default) | vector
Input scaling factors, specified as a vector of length Nu, where
Nu is the number of inputs in the original model
sys
.
Use this option to emphasize specific input channels in sys
. The
software evaluates the modal contributions for the scaled system.
This affects only the normalized DC contribution (R.DCGain
). For
the input scaling factor Du and output scaling
factor Dy, the normalized DC contribution of
Gk(s) in continuous
time is obtained as
In discrete time, the software uses the first time samples Gk(1) and G(1).
OutputScaling
— Output scaling factors
[]
(default) | vector
Output scaling factors, specified as a vector of length Ny, where
Ny is the number of outputs in the original model
sys
.
Use this option to emphasize specific output channels in sys
. The
software evaluates the modal contributions for the scaled system.
This affects only the normalized DC contribution (R.DCGain
). For
the input scaling factor Du and output scaling
factor Dy, the normalized DC contribution of
Gk(s) in continuous
time is obtained as
In discrete time, the software uses the first time samples Gk(1) and G(1).
ModeTol
— Accuracy of computed modes
1e-12
(default) | positive scalar
Tolerance for identifying converged eigenvalues in Krylov-Schur iterations, specified as a positive scalar.
SepTol
— Relative accuracy of modal contribution
1e-12
(default) | scalar between 0 and 1
Relative accuracy of modal contribution, specified as a scalar between 0 and 1.
This option limits the condition number of the block diagonalizing transformation to
roughly SepTol
/eps
. Increasing
SepTol
helps yield smaller modal components at the expense of
accuracy.
Version History
Introduced in R2023b
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