The Universal Java Matrix Package (UJMP) is an open source Java library that provides sparse and dense matrix classes, as well as a large number of calculations for linear algebra like matrix multiplication or matrix inverse. Operations like mean, correlation, standard deviation, replacement of missing values or mutual information are also supported.

Matrices can be imported from and exported to a large number of file formats, also linking to JDBC databases is supported. The Universal Java Matrix Package supports multidimensional matrices as well as generic matrices with a specified object type and can also handle very large matrices even when they do not fit into memory.