(j3.2006) IEEE modules and NORM2

[Jim Xia]

May I ask what compiler was used in this study?

Cheers,

Jim Xia

RL Fortran Compiler Test
IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7
Phone (905) 413-3444  Tie-line 313-3444
email: jimxia at ca.ibm.com
D2/YF7/8200 /MKM

j3-bounces at j3-fortran.org wrote on 10/09/2008 01:51:36 PM:

> [image removed] 
> 
> (j3.2006) IEEE modules and NORM2
> 
> Van Snyder 
> 
> to:
> 
> j3
> 
> 10/09/2008 01:54 PM
> 
> Sent by:
> 
> j3-bounces at j3-fortran.org
> 
> Please respond to Van.Snyder, fortran standards email list for J3
> 
> Dick Hanson sent me the following interesting result.  It confirms the
> usefulness of the IEEE modules, and points out that when vendors get
> around to implementing NORM2 they shouldn't just use level 1 reference
> BLAS.
> 
> Van
> 
>         As an illustration for using the IEEE modules, I coded up DNRM2 
of the
>         BLAS.  The basic idea is simple:  Do the easy loop first and 
then
>         check for exceptions and fix things up.  For that I used Jim 
Blue's
>         1978 TOMS algorithm.  It prompted the question about the static
>         constants.
> 
>         The basic conclusions are that this IEEE version is always more
>         accurate.   It pulls away from Hammarling's LAPACK version at 
about
>         n=40 and gets steadily faster, perhaps to factors or 30 or more. 
 This
>         is on the IBM PowerStation.
> 
>         So this is good news for the IEEE module supporters, especially 
John
>         Reid.  The example he gave in M, R and C for the planar length 
is
>         always going to be a lot slower than simply scaling.  This is 
because
>         there is overhead in the calls to get and set flags.  For DNRM2 
that
>         overhead time gets swamped out by compute time at about n=40.
> 
> 
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