Re: Generalized Eigenvector and Singular Value Decompositions
- To: mathgroup at christensen.cybernetics.net
- Subject: [mg319] Re: [mg304] Generalized Eigenvector and Singular Value Decompositions
- From: Richard Mercer <richard at rmercer.wright.edu>
- Date: Mon, 12 Dec 1994 14:30:38 -0500
Mark Kotanchek complains about matrix capabilities of Mathematica: I agree, and feel this is definitely a weak area that could be significantly improved with less effort than many others, and one that is crucial in applied mathematics. I wonder if some peoples' mathematical interests are taking precedence over customer needs when WRI decides where to place R&D efforts? All this is of course in the context of a program often taken (over the muffled screams of the developers) as an attempt to be all things to all people. However: > 1) the SVD of a 6x6 complex-valued matrix requires > 0.8 seconds on my NeXTstation -- which is IMHO > excessive; If it takes 2 hours to do a large matrix, then you may have a complaint. Taking 0.8 seconds to do anything is not a valid complaint, especially given the quirks of timing. My NeXTstation yield 0.15 seconds for 10 repetitions of applying SingularValues to a random 6x6 matrix as measured by the Timing command. On the other hand, doing it just once gives 0.4 seconds (no output) or 1.8 second (with output) through the in-window time display. They are all measuring different things, none of them particularly useful except for comparisons between machines. Richard Mercer