## Edit Material Coordinates

Select **Mesh→Edit→Material Coordinates...** to open the `Material Coordinate Editor`

If no material coordinate model is present, or you wish to change the current one, press the

**Import**button to select a file.The material coordinate model is written in high-level syntax (sympy) and compiled into C code. If you author a new material model, the model will first have to be compiled (

**Compile**button). This requires that the compilation environment has been set up on your server. For installation and setup instructions, see CompilingModels.

Use the

**Export**button to save the current model and edit the current model in a text editor. You may use an existing model file as a template for a new one.- You can only change properties for models that you authored

Right-click the current model (top), such as

**MatCoordStandard**, and select 'Add Variable Inside' to create and name intermediate symbolic or evaluated variables and write the equations that define the`Dependent variable`for this model, which is**dY_dMatl**, in terms of the`Independent variables`. These include`World Coordinates`**X**,`Global rectangular Cartesian Coordinates`**Y**, and their first and second derivatives with respect to local`xi`coordinates**dX_dXi**,**d2X_dXi2**,**dY_dXi**,**d2Y_dXi2**.**dY_dMatl**is an orthogonal rotation matrix that transforms`Global rectangular Cartesian coordinates`**Y**to locally orthonormal`Material coordinates`**Matl**Equations are entered using Sympy

**View**-->**View equations**displays a complete listing of the Sympy equations defining the model.The

**Compile**tab is where C code is generated from the Sympy model and compiledClick the

**Compile**button to compile the model on the default serverClick

**View**-->**View Source Code**to generate and view a C code listing of the model

Click the '+' next to

**Parameters**in the model. A list of adjustable model parameters should appear.Parameters are entered with their names in <anglebrackets> in the equations

Select a

`parameter`in the listYou can edit its

`Description`, specify its default value to be defined by a constant`value`or a`field variable`or a`field variable derivative`.You can also add exceptions using the

**Add exception in...**popup menu that allows alternative parameter values or fields to be specified according to a prescribed`element list`or a prescribed`field range`for a specified field variable.

Click the

**OK**button to submit the`Material Coordinate Transformation`model to your current Continuity session.