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The HSL Mathematical Software Library

Over 60 years of getting the right answer

HSL (formerly the Harwell Subroutine Library) is a collection of state-of-the-art packages for large-scale scientific computation written and developed by the Computational Mathematics Group at the STFC Rutherford Appleton Laboratory and other experts. HSL offers users a high standard of reliability and has an international reputation as a source of robust and efficient numerical software. Among its best known packages are those for the solution of sparse linear systems of equations and sparse eigenvalue problems. MATLAB interfaces are offered for selected packages.

The Library was started by Mike Powell in 1963, originally to support computing at the Atomic Energy Research Establishment at Harwell. Development moved the the neigbouring Rutherford Appleton Laboratory in 1990. The library has continually evolved over the years, with new software being added, and obsolete software being archived, regularly. Jennifer Scott has produced a short survey on the first 60 years of the libary. Details of the latest release can be found here.

If you are interested in our optimization or nonlinear equation solving packages, our work in this area is released in the GALAHAD library.


We currently offer three types of licence:
HSL packages are available at no cost for academic research and teaching. See download links for individual packages in the catalogue.
Commercial (per seat)
For use internal to your company we offer per seat licences. Please contact us for a price.
Commercial (incorporation)
For incorporation in software that you distribute, we offer an incorporation licence. Pricing is done on a case-by-case basis. Please contact us to discuss your requirements.

Many older packages are available at no cost for personal academic or commercial (non incorporation) use via the HSL Archive.

More information on licensing can be found on our licensing page.