## Choose Linearization Tools

### Choosing Simulink Control Design Linearization Tools

Simulink® Control Design™ software lets you perform linear analysis of nonlinear models using a user interface, functions, or blocks.

Linearization ToolWhen to Use
Model Linearizer
• Interactively explore Simulink model linearization under different operating conditions.

• Diagnose linearization problems.

• Batch linearize for varying model parameter values.

• Automatically generate MATLAB® code for batch linearization.

`linearize`
• Linearize a Simulink model for command-line analysis of poles and zeros, plot responses, and control design.

• Batch linearize for varying model parameter values and operating points.

`slLinearizer`

Batch linearize for varying model parameter values, operating points, and I/O sets.

Linear Analysis Plots blocks
• Visualize linear characteristics of your Simulink model during simulation.

• View bounds on linear characteristics of your Simulink model on plots.

• Optionally, check that the linear characteristics of your Simulink model satisfy specified bounds.

Note

Linear Analysis Plots blocks do not support code generation. You can only use these blocks in `Normal` simulation mode.

### Choosing Exact Linearization Versus Frequency Response Estimation

In most cases, to obtain a linear approximation of a Simulink model, you should use exact linearization instead of frequency response estimation.

Exact linearization:

• Is faster because it does not require simulation of the Simulink model.

• Returns a parametric state-space model.

Frequency response estimation returns frequency response data. To create a transfer function or a state-space model from the resulting frequency response data, you must fit a model to the data using System Identification Toolbox™ software.

Use frequency response estimation:

### Linearization Using Simulink Control Design Versus Simulink

How is Simulink `linmod` different from Simulink Control Design functionality for linearizing nonlinear models?

Although both Simulink Control Design and Simulink `linmod` perform block-by-block linearization, Simulink Control Design functionality is enhanced by a more flexible user interface and Control System Toolbox™ numerical algorithms.

Graphical-user interfaceYes. See Linearize Simulink Model at Model Operating Point.No
Flexibility in defining which portion of the model to linearizeYes. Lets you specify linearization I/O points at any level of a Simulink model, either graphically or programmatically without having to modify your model. See Linearize at Trimmed Operating Point.

No. Only root-level linearization I/O points, which is equivalent to linearizing the entire model.

Requires that you add and configure additional Linearization Point blocks.

Open-loop analysisYes. Lets you open feedback loops without deleting feedback signals in the model. See Compute Open-Loop Response.Yes, but requires that you delete feedback signals in your model to open the loop
Control linear model state orderingYes. See Order States in Linearized Model.No
Control linearization of individual blocks Yes. Lets you specify custom linearization behavior for both blocks and subsystems. See When to Specify Individual Block Linearization.No
Linearization diagnosticsYes. Identifies problematic blocks and lets you examine the linearization value of each block. See Linearization Troubleshooting Overview.No
Block detection and reductionYes. Block reduction detects blocks that do not contribute to the overall linearization yielding a minimal realization.No
Control of rate conversion algorithm for multirate modelsYes No

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