SPARTA comes with no warranty of any kind. As each source file states in its header, it is a copyrighted code that is distributed free-of-charge, under the terms of the GNU Public License (GPL), or sometimes (by request) under the terms of the GNU Lesser General Public License (LGPL). This is often referred to as open-source distribution - see www.gnu.org or www.opensource.org. The legal text of the GPL or LGPL is in the LICENSE file that is included in the SPARTA distribution.
Here is a summary of what the GPL means for SPARTA users:
(1) Anyone is free to use, modify, or extend SPARTA in any way they choose, including for commercial purposes.
(2) If you distribute a modified version of SPARTA, it must remain open-source, meaning you distribute it under the terms of the GPL. You should clearly annotate such a code as a derivative version of SPARTA.
(3) If you release any code that includes SPARTA source code, then it must also be open-sourced, meaning you distribute it under the terms of the GPL.
(4) If you give SPARTA files to someone else, the GPL LICENSE file and source file headers (including the copyright and GPL notices) should remain part of the code.
In the spirit of an open-source code, these are various ways you can contribute to making SPARTA better. You can send email to the authors on any of these items.