High quality theoretical foundations, good solid code for Matlab and some fortran routines, I like the fact the authors think about loops and iterators the way I do, as a programmer, but also have the time to write out the material as a mathematician, often these two things are totally seperate in pure math and programming books.

Simply a must for anyone doing any matrix programming, as the ideas and implementations are easily portable to other matrix/array based langauges such as Gauss and R.