Derived Values, Evaluation Groups, and Tables

You can integrate or compute the average, maximum, or minimum of any quantity to compute derived quantities such as total flux; charges; inductances; reaction forces; and average, maximum, and minimum values. You can also measure geometric quantities such as volumes, surfaces, and distances.

Use (

) to define evaluations of numerical results — globally, in a point, or integrated quantities. The values appear in a table in the Table window, where you have different options for the precision and notation of the numerical values (see The Table Window and Tables Node below). For 2D and 3D plots, you can also get numerical results directly in a table by clicking the plot.

For all derived values, you can also apply an operator on a data series (from a parametric or Time Dependent study) to compute, for example, the temporal average of a quantity in a point of the domain for which a time-dependent solution is computed. In addition to the average, you can also compute the integral, maximum, minimum, RMS (root mean square), standard deviation, or variance of the data series. The derived values nodes use datasets (typically solution datasets) that provide the data from which the derived values are computed. If needed, specify the frame and geometry to use in the dataset’s window.


	Depending on the physics interface included in the model, not all derived values (numerical evaluation) types may be available. To see all numerical evaluation types, select the All Numerical Evaluation Types check box in the Show More Options dialog box.


	For evaluating derived values in a batch job for cluster computing, for example, see Evaluate Derived Values.

Getting Numerical Results Directly


	For 3D and 2D models, the numerical value of the current plot can be displayed by clicking anywhere in the model geometry. For a 3D model, the value is for the point where a ray projected from the point clicked hits the geometry. COMSOL Multiphysics displays the value at that point along with the point’s coordinates in a row in an Evaluation 2D or Evaluation 3D table in the Table window. Each click adds a row to the table. From the Table window, you can plot or copy the table data to a clipboard like any other table.

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See Derived Value Types for links to the datasets.

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Common Results Node Settings