Equation Display

With the Equation Display () node you can enter pretty-print equations in LaTeX that show up in the Equations section of a physics interface or feature in the Model Builder.

To add an Equation Display, first add a node where it is available, for example, components, physics interfaces, multiphysics interfaces, features, or properties, then right-click the node and choose it from the context menu.

You can also add an Equation Display under the Auxiliary Definitions branch. This is the button available on the Home toolbar. See Equation Display (Auxiliary Definitions).

The Settings window has the following sections:

Declaration

If you select the Allow named references to equation check box, the Name field will be the name used to reference to this equation display from other equation displays using the symbref command. If you clear this check box, the tag of the equation display will be used. Apart from named references, the automatic or given name is also used when you use equation displays in user input groups. In this case it is important that the name is not in conflict with other equation display names in the same physics feature or physics property also used in input groups. See also References in Equation Expressions.

Equation

Enter the LaTeX-encoded expressions in the Enter equation in LaTeX syntax field. There are tools you can use to get help entering specific LaTeX commands.

•	Press Ctrl+Space to get a list of predefined operations to choose from.

•	Click the Add Expression () or Replace Expression () toolbar buttons for the same list of operations.

•	Click the Add Expression toolbar button to concatenate expressions to the entered expression, and Replace Expression to overwrite.

•	See a preview of the entered expression under the Equation preview.

•	Use the Refresh equation preview button () to update this preview to force it to be up to date with the expression entered in the Enter equation in LaTeX syntax field.

References in Equation Expressions

It can be useful to reuse parts of equations or combine multiple equation expressions into one equation. This is achieved using the syntax

\symbref(eq)

in an expression. This inserts the equation expression from the equation display node with the name eq. This referenced node can be local (that is, defined in the same feature or property as the referee), or it can be defined under the Definitions Library branch. It is useful to access equations from the Definitions Library for a file that has been imported under the External Resources node. In this case, the name of the equation should be prefixed with the tag of the import node, for example:

\symbref(imp1.eq)

It is also possible to insert the name of a dependent variable into an equation expression. If the default name of a dependent variable is u, then use the following syntax to access the current user-defined name of that dependent variable:

\symbref(dep.u)

See Mathematical Symbols and Special Characters in the COMSOL Multiphysics Reference Manual for information about available LaTeX symbols and commands.

GUI options

This section controls how the equation is displayed in the user interface. To include an image under the equation select the Include image below equation check box and enter a file path to an Image file. Select the Exclude from equation section check box if the equation should not be displayed in the standard Equation section.

This option is useful when the Equation Display node is created only to be displayed in a user input group.