If you are interested in matrix calculations for mathematical and scientific applications I suggest you used a java library to do that e.g. parallerl-colt http://dst.lbl.gov/ACSSoftware/colt/
To use this in mendix you need to have a java action - https://docs.mendix.com/howto/logic-business-rules/extending-your-application-with-custom-java
Do you have an example of a matrix calculation you would want to perform?
If it's a complex calculation (e.g. determining the determinant for arbitrarily large matrices) for which a verified solution exists in Java, I would create a Java action, copy the Java solution in the action and map the Mendix data structure to the Java data structure by writing some Java glue code.