[comp.arch] Accuracy results on various computers?

urjlew@ecsvax.uncecs.edu (Rostyk Lewyckyj) (01/07/89)

In article <352@loligo.fsu.edu>, mccalpin@loligo.fsu.edu (John McCalpin) writes:
> 
>         ...          .  An interesting example (which 
> I referred to in my paper in SUPERCOMPUTING a few months back) is the
> 1000x1000 LINPACK benchmark test. The matrix is fairly poorly
> conditioned, so requires some care in 32-bit mode. I include a sample 
> of my results below.  The numbers scale so that the absolute value
> of the exponent of the RMS error is about the number of significant
> digits of accuracy in the solution.
> 
> machine		       precision	    RMS error in solution (*)
> ---------------------------------------------------------------------
> Cyber 205 / ETA-10	32-bit			2.22521256e-01
> IBM 3081		32-bit			2.37465184e-03
> IEEE standard		32-bit			2.82104476e-04
> ---------------------------------------------------------------------
> Cyber 205 / ETA-10	64-bit			1.32111221e-08
> Cray X/MP		64-bit			2.47078473e-11
> IEEE standard		64-bit			2.27274978e-13
> ---------------------------------------------------------------------
> Cyber 205/ETA-10	128-bit			1.60755733e-22
> Cray X/MP		128-bit			4.15861230e-26
> 
> NOTES:
>     (*) The solution vector consists of 1000 identical elements = 1.0
>     (1) The IEEE standard was run on a Sun 3/280, which had passed
> 	the PARANOIA benchmark test.


Here at the Academic Computing Services for the University of
North Carolina at Chapel Hill we have various IBMs and a CONVEX C220.
Also our researchers use the Cray X/MP at Pittsburgh and theIBM 3090
at Cornell. Therefore it would be very interesting for us if you or 
anyone else could please post or point to published results for an 
IBM 3081 or preferably 3090, running under the MVS/XA operating 
system, using the VS FORTRAN v1.3 compiler, and version 2 libraries,
and also the CONVEX.
I would like to see the results for 32, 64, and 128 bit reals. i.e.
REAL*4, REAL*8 and REAL*16. 
This would allow comparisons with the Cray X/MP results which
you have posted here.
I would also like to know the Paranoia results for the above three
machines as well as any comparisons of the quality of the mathematical 
libraries provided with the FORTRAN language systems .
In the case of the IBM I am looking for comparisons against the
new version 2 libraries not the older version.
Please post anything you may have in this area and also send
me copies by mail.
-tnx.
-----------------------------------------------
  Reply-To:  Rostyslaw Jarema Lewyckyj
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