The unit MATRIX offers some of the most important operations to manage and process two-dimensional real-valued and integer matrices. The object oriented approach of the unix MATRIX hides all the stuff dealing with array addressing and memory management. Thus the user may fully concentrate on his/her work. The unit MATRIX offers solutions for the following tasks: creation and management of matrices, filling and copying matrices, matrix arithmetics, determination of statistical parameters about the matrix elements, inversion of a square matrix, sorting of matrix elements