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Developer(s) Timothy A. Davis
Initial release January 1994
Stable release
5.7.4 / February 1, 2016; 12 months ago (2016-02-01)
Development status Active
Written in C
Operating system Cross-platform
Type Mathematics, Linear Algebra
License GNU Lesser General Public License or BSD License

UMFPACK /ˈʌmfpæk/ is a set of routines for solving unsymmetric sparse linear systems of the form Ax=b, using the Unsymmetric MultiFrontal method (Matrix A is not required to be symmetric). Written in ANSI/ISO C and interfaces with

It appears as a built-in routine (for lu, backslash, and forward slash) in MATLAB, and includes a MATLAB interface, a C-callable interface, and a Fortran-callable interface. Note that "UMFPACK" is pronounced in two syllables, "Umph Pack". It is not "You Em Ef Pack"[citation needed].

The BLAS: Basic Linear Algebra Subprograms[edit]

UMFPACK has installation options to use the many versions of the BLAS, or no BLAS at all. The BLAS is what UMFPACK relies on to get high performance on a wide range of computers. If at all possible, use the BLAS. If your BLAS uses 64-bit integers, compile with -DBLAS64. You can also edit the UFconfig.h (SuiteSparse_config.h starting from version 4.0.0) file as needed to include this definition.


The license of UMFPACK has changed in the last two years from a BSD license to LGPL, and finally in the last version 5.2 to a GPL license. Some versions of the software have been retroactively placed under the LGPL, so different licensed versions can be found.

External links[edit]