lsqr_f90.readme

比较经典的求解线性方程的方法 原理是C.C. Paige and M.A. Sauders等你提出的

lsqr_f90.README

The software for LSQR (f90 version) is provided by SOL, Stanford University
under the terms of the OSI Common Public License (CPL):
http://www.opensource.org/licenses/cpl1.0.php

07 Sep 2007: First f90 files provided by Eric Badel <[e-mail]>.
16 Sep 2007: More f90 features added by MAS.
             "implicit none" everywhere.
             data statements eliminated.
             But we're still stuck with subroutine Aprod, the f77 method
             for forming matrix-vector products A*x, A'*y.
16 Sep 2007: First set of f90 files available for download from SOL.

Please send comments to Michael Saunders, SOL, Stanford University
                        [e-mail]  650-723-1875
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The f90 version of LSQR involves the following files:

   lsqr.f90
   lsqrblas.f90   (not needed if you have BLAS-1)
   lsqrcheck.f90
   lsqrtest.f90
   LSQR.txt       (example output file from an Intel Xeon system
                   compiled with g95 on Linux Redhat 9)


To compile the code and run the test program on Linux or Unix,
proceed as follows:

   g95 -o lsqrtest lsqr.f90 lsqrcheck.f90 lsqrtest.f90 lsqrblas.f90
   ./lsqrtest
   grep appears LSQR.txt

"LSQR  appears to be successful" should occur 18 times.
"LSQR  appears to have failed" might occur for the most
ill-conditioned problem, but this is not cause for alarm
if ||A'r|| is very small (~= 1e-12).