For information about the Matrix Template Library see http://www.osl.iu.edu/research/mtl/
See also http://en.wikipedia.org/wiki/Matrix_Template_Library on WikiPedia
How does this compare with
The Open-Source, Extensible Spacecraft Simulation And Modeling Environment (Open-SESSAME) http://spacecraft.sourceforge.net/ by A.J. Turner et. al.?
Better / worse / just different?
The first one is a Template library. BoostuBlas is an alternative, one of the BoostLibraries.
The second one I do not know, but seems to be for a specific problem. -- JohnFletcher