[Lapackpp-devel] SVD that ignores U, Sigma or VT

[Jacob \(Jack\) G. <jg...@cs...>]

Hi,

 

I'm writing some code that only uses data from VT of an SVD, and don't need
the data in U and Sigma.  Although I can ignore it; the resulting U is
significantly large (512^2x512^2), which is too large a matrix for the
system to handle; and is clearly a waste.

 

I've noticed that there is a function that ignores both U and VT, by
essentially setting ldv and ldu to 0, that seemingly tells LAPACK to ignore
the data.  Maybe it would be better just to use a single LaSVD_IP function,
and allow uninitialized LaGenMat[Double/Complex] as input.  If, for example
U is declared with the default constructor, since U.gdim(0) == 0, I would
guess that LAPACK will ignore writing output to U.

 

Any thoughts on this?

 

Jack