Specify the model you want to reduce by selecting from theModeldrop-down list. The list includes all models currently in theData Browser. To get a model from the MATLAB workspace into theData Browser, on theModel Reducertab, clickImport Model. You can import any:

Specify the number of states in the reduced-order model. Any value is permitted that falls between the number of unstable states in the model and the number of states in the original model. If you specify a single value,Model Reducercomputes and displays the responses of a model of that order. If you specify multiple values,Model Reducercomputes models of all specified orders and displays their responses on the same plot. To store reduced models in theData Browser, click.

For more information, seeBalanced Truncation Model Reduction.

Example:5

Example:4:7

Example:[3,7,10]

You can choose between absolute and relative errors by selecting the appropriate option inError Bound. Setting it toabsolutecontrols the absolute error $${\Vert G-G_r\Vert }_{\infty }$$while setting it torelativecontrols the relative error $${\Vert G^{-1}\left(G-G_r\right)\Vert }_{\infty }$$. Relative error gives a better match across frequency while absolute error emphasizes areas with most gain.

For more information, seeBalanced Truncation Model Reduction.

WhenPreserve DC Gainis checked, the DC gain of the reduced model equals the DC gain of the original model. When the DC behavior of the model is important in your application, leave this option checked. Uncheck the option to get better matching of higher-frequency behavior.

For more information, seeBalanced Truncation Model Reduction.

By default,Model Reduceranalyzes Hankel singular values across all frequencies. Restricting this analysis to a particular frequency range is useful when you know the model has modes outside the region of interest to your particular application. When you apply a frequency limit,Model Reducerdetermines which states are the low-energy states to truncate based on their energy contribution within the specified frequency range only.Focus on rangeis only available whenError Boundis set toabsolute.

限制contri状态的分析butions to a particular frequency range, checkFocus on range. Then, drag the vertical cursors on the response plot to specify the frequency range of interest. Alternatively, enter a frequency range in the text box as a vector of the form[fmin,fmax]. Units arerad/TimeUnit, whereTimeUnitis theTimeUnitproperty of the model you are reducing.

Specify the model you want to reduce by selecting from theModeldrop-down list. The list includes all models currently in theData Browser. To get a model from the MATLAB workspace into theData Browser, on theModel Reducertab, clickImport Model. You can import any:

For more information, seeMode-Selection Model Reduction.

Enter the frequency of the slowest dynamics to preserve in the reduced model. Poles with natural frequency below this cutoff are eliminated from the reduced model.

Enter the frequency of the fastest dynamics to preserve in the reduced model. Poles with natural frequency above this cutoff are eliminated from the reduced model.

Specify the model you want to reduce by selecting from theModeldrop-down list. The list includes all models currently in theData Browser. To get a model from the MATLAB workspace into theData Browser, on theModel Reducertab, clickImport Model. You can import any:

Set the tolerance for pole-zero cancellation by using the slider or entering a value in the text box. The value determines how close together a pole and zero must be forModel Reducerto eliminate them from the reduced model. Moving the slider to the left or entering a smaller value in the text box simplifies the model less, by cancelling fewer poles and zeros. Moving the slider to the right, or entering a larger value, simplifies the model more by cancelling poles and zeros that are further apart.

For more information, seePole-Zero Simplification.