# view

## Description

Use `view`

to graphically analyze the model and select a model
order reduction criteria from a model order reduction task created using `reducespec`

. For
`BalancedTruncation`

and `SparseBalancedTruncation`

objects, you can visualize the state contributions as either Hankel singular values or
normalized state energies. For the full workflow, see Task-Based Model Order Reduction Workflow.

`view(`

plots the default plot type for the
model order reduction algorithm of `R`

)`R`

. For balanced truncation
methods, this syntax plots Hankel singular values and associated error bounds.

`view(___,Axes=AX)`

plots on the `Axes`

object in the current figure with the handle `AX`

. Use this input
argument after any of the input argument combinations in the previous syntaxes. For more
information about customizing axes, see Axes Properties.

`view(___,`

specifies
additional options for customizing the appearance of Hankel singular value plots. For
example, `Name=Value`

)`view(R,"sigma",Axes=AX,YScale="Linear")`

plots the Hankel
singular values into the axes with handle `AX`

using a linear scale for
*y* axis. For a list of available options, see `hsvoptions`

.

`view(`

returns help specific to the
model order specification object `R`

,"-help")`R`

. The returned help shows plot
types and syntaxes applicable to `R`

.

## Examples

## Input Arguments

## Output Arguments

## References

[1] Benner, Peter, Jing-Rebecca Li,
and Thilo Penzl. “Numerical Solution of Large-Scale Lyapunov Equations, Riccati Equations, and
Linear-Quadratic Optimal Control Problems.” *Numerical Linear Algebra
with Applications* 15, no. 9 (November 2008): 755–77.
https://doi.org/10.1002/nla.622.

[2] Benner, Peter, Martin Köhler, and
Jens Saak. “Matrix Equations, Sparse Solvers: M-M.E.S.S.-2.0.1—Philosophy, Features, and
Application for (Parametric) Model Order Reduction.” In *Model
Reduction of Complex Dynamical Systems*, edited by Peter Benner, Tobias Breiten,
Heike Faßbender, Michael Hinze, Tatjana Stykel, and Ralf Zimmermann, 171:369–92. Cham:
Springer International Publishing, 2021.
https://doi.org/10.1007/978-3-030-72983-7_18.

[3] Varga, A. “Balancing Free
Square-Root Algorithm for Computing Singular Perturbation Approximations.” In *[1991] Proceedings of the 30th IEEE Conference on Decision and
Control*, 1062–65. Brighton, UK: IEEE, 1991.
https://doi.org/10.1109/CDC.1991.261486.

[4] Green, M. “A Relative Error Bound
for Balanced Stochastic Truncation.” *IEEE Transactions on Automatic
Control* 33, no. 10 (October 1988): 961–65.
https://doi.org/10.1109/9.7255.

## Version History

**Introduced in R2023b**

## See Also

### Functions

`reducespec`

|`process`

|`getrom (balanced)`

|`view (modal)`

|`getrom (modal)`

|`view (ncf)`

|`getrom (ncf)`