Specifying Equation Coefficients and Material Properties

To specify an equation coefficient or a material property, enter a value or an expression directly in the corresponding field. Such expressions can contain:

•	Numerical values.

•	Units (see Using Units).

•	Built-in Mathematical and Numerical Constants.

•	Spatial coordinates, time, and the dependent variables in any physics feature in the model as well as the spatial derivatives and time derivatives.

•	Physical Constants — built-in universal physical constants.

•	User-defined parameters, variables, coupling operators, and functions, including external functions and MATLAB® functions (requires the COMSOL LiveLink™ for MATLAB®). See Operators, Functions, and Constants.

•	Built-in functions and operators such as d and mean.

You can use these types of variables, constants, functions, and operators in all settings for the physics interfaces; many types of variables are also available anywhere in the model.

In most cases where you can enter an expression, you can press Ctrl+Space to choose from a number of applicable variables, parameters, functions, operators, and constants that you can insert into the expression at the position of the cursor.