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 High Performance Computing Linpack Benchmark (HPL)
 HPL 2.0 - September 10, 2008
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 History

 - 09/09/00 Public release of Version 1.0

 - 09/27/00 A couple of mistakes in the  VSIPL  port have been
 corrected.  The tar file as well as the web site were updated
 on September 27th, 2000.  Note  that  these problems were not
 affecting the BLAS version of the software in any way.

 - 01/01/04 Version 1.0a
 The  MPI  process grid  numbering  scheme  is now an run-time
 option.
 The inlined assembly  timer  routine that caused the compila-
 tion to fail when using  gcc  version 3.3  and above has been
 removed from the package.
 Various building problems on the T3E have been fixed;  Thanks
 to Edward Anderson.

 - 15/12/04 Version 1.0b
 Weakness of the pseudo-random matrix generator found for pro-
 blem sizes being power of twos and larger  than 2^15;  Thanks
 to Gregory Bauer. This problem has not been fixed. It is thus
 currently recommended to  HPL  users willing to test matrices
 of size larger than 2^15 to not use power twos.

 When the matrix size is such that one needs  > 16 GB  per MPI
 rank,  the  intermediate  calculation  (mat.ld+1) * mat.nq in
 HPL_pdtest.c  ends up  overflowing  because  it is done using
 32-bit arithmetic.  This issue has been fixed by  typecasting
 to size_t; Thanks to John Baron.

 - 09/10/08 Version 2.0

 Piotr Luszczek changed to 64-bit RNG, modified files:
 -- [M] include/hpl_matgen.h
 -- [M] testing/matgen/HPL_ladd.c
 -- [M] testing/matgen/HPL_lmul.c
 -- [M] testing/matgen/HPL_rand.c
 -- [M] testing/ptest/HPL_pdinfo.c

 For a motivation for the change, see:
    Dongarra and Langou, ``The Problem with the Linpack
    Benchmark Matrix Generator'', LAWN 206, June 2008.

 -- [M] testing/ptest/HPL_pdtest.c  --

 Julien Langou changed the test for correctness from
      ||Ax-b||_oo / ( eps * ||A||_1  * N            )
      ||Ax-b||_oo / ( eps * ||A||_1  * ||x||_1      )
      ||Ax-b||_oo / ( eps * ||A||_oo * ||x||_oo * N )
 to the normwise backward error
      || r ||_oo / ( eps * ( || x ||_oo * || A ||_oo + || b ||_oo ) * N )
 See:
  Nicholas J. Higham, ``Accuracy and Stability of Numerical Algorithms'',
  Society for Industrial and Applied Mathematics, Philadelphia, PA, USA,
  Second Edition, pages = xxx+680, ISBN = 0-89871-521-0, 2002.

 Note that in our case || b ||_oo is almost for sure
 1/2, we compute it anyway.

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