The Littlewood-Richardson Calculator is a program designed to compute Littlewood-Richardson coefficients. This program is written in the C language to make the computation as efficient as possible. The program can compute single Littlewood-Richardson coefficients, products of Schur functions, or skew Schur functions. In addition it can compute products in the small quantum cohomology ring of a Grassmann variety. The software package also includes a program that performs fast computation of the more general multiplicative structure constants of Schubert polynomials.

The Littlewood-Richardson calculator has been integrated in the Sage-Combinat package for the Sage Mathematics Software System. You may prefer to use the Littlewood-Richardson Calculator in this way to take advantage of the additional functions in Sage. The Littlewood-Richardson Calculator also has a Maple interface which is included in the software package distributed here. This interface uses the same notation as the SF package of John Stembridge, to make it easier to use both packages at the same time.

The Littlewood-Richardson Calculator is open source software (under the GNU General Public License). To install it, download the file

lrcalc-1.2.tar.gzand unpack it using the (unix) command:

% tar zxvf lrcalc-1.2.tar.gz

This will create a directory named `lrcalc-1.2`

. Now
change to this directory and run the following commands:

% cd lrcalc-1.2 % ./configure % make % sudo make installThis will install the programs

`lrcalc`

and `schubmult`

in the
directory `/usr/local/bin`

. Please refer to
the `README`

file in
the `lrcalc-1.2`

directory for more details, and see
the `ChangeLog`

file for
a list of bug fixes, enhancements, and contributors. Special thanks
go to Nicolas Thiery and Jean-Pierre Flori for adding the GNU automake
system to the software package. People interested in writing
enhancements to the software may wish to obtain the GIT repository
from `bitbucket.org`

, which is done with the following command:
% git clone https://asbuch@bitbucket.org/asbuch/lrcalc.git

I will be grateful for any comments or bug reports for this package. Enjoy!

During the development of this software, the author was partially supported by NSF grants DMS-0070479, DMS-0603822, DMS-0906148, and DMS-1205351.