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From: "John D'Errico" <woodchips@rochester.rr.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: nonnegative Ax=b lsq for large, sparse A.
Date: Fri, 26 Jun 2009 15:17:02 +0000 (UTC)
Organization: John D'Errico (1-3LEW5R)
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"Tim Davis" <davis@cise.ufl.edu> wrote in message <h22o30$gi5$1@fred.mathworks.com>...
> 
> John ... which version MATLAB are you using?  I tried your example on a Pentium 4 running MATLAB 7.8 (R2009a) and sparse backslash took just 4.2 seconds.  lsqlin took 0.9 seconds (with no "opts" argument since you didn't say what it was).  SPQR_SOLVE took 0.6 seconds, but of course A\b and spqr_solve return x with negative values, whereas lsqlin respects the lower bound lb.

I'm usually running an older Mac, so R2007b is the
latest I can use, except when I can pry the laptop away
from the household CEO.

Worse, I was kibbitzing a bridge event on the bbo
vugraph at the time, so that was probably stealing a
few processor cycles away.

John