Add a Matrix Inverse node () under Definitions>Variable Utilities (if Group by Type is active; otherwise, directly under Definitions) to define a variable as the inverse of a square input matrix. You add it by right-clicking the Definitions node and choosing Variable Utilities>Matrix Inverse or by right-clicking the Variable Utilities node and choosing Matrix Inverse.

You can define a Label for the node, and a namespace for variables using the Name field. For the Geometry Entity Selection, see About Selecting Geometric Entities.

In addition, the Settings window for a Matrix Inverse node contains the following section:

In this section, you define the input matrix to invert. Choose a Matrix format: Full (the default), Symmetric, or Hermitian. For a symmetric or Hermitian matrix, you only enter the upper-triangular part of the matrix. A Hermitian matrix (or self-adjoint matrix) is a complex square matrix that is equal to its own conjugate transpose. From the Matrix size list, choose a matrix size from 1x1 to 9x9; the enter the matrix elements in the table below.

The resulting matrix inverse is available as a list of scalar variables with names <name>.invT<i><j>, where <name> is the namespace set in the Name field, and <i> and <j> are integer indices. The input matrix with names <name>.T<i><j>, as well as the matrix determinant <name>.detT are also made available. Note that the determinant is not computed for matrices of size 4x4 or larger; if required, use a Matrix Decomposition node instead.

You can use individual components where variable expressions are allowed, but also evaluate all variables at once using a matrix evaluation node under Derived Values. For example, select matinv1.invT under Model>Component 1>Definitions>Matrix Inverse 1>Matrix inverse if it the node has been defined as Matrix Inverse 1 with the name matinv1 in Component 1.