[J3] New reference BLAS NRM2 routines

Toon Moene toon at moene.org
Thu Oct 11 16:41:27 EDT 2018

On 10/09/2018 04:38 PM, Steve Lionel via J3 wrote:

> On 10/9/2018 10:31 AM, Robert Corbett wrote:

>> I still find the authors' claim dubious.
>> They claim adding the option fp:precise fixed the problem.
>> Would the option fp:precise make
>> the compiler respect parentheses?
> That option disables a lot of optimizations, so it would not astonish me 
> if that were among them.

GNU Fortran takes the opposite approach, which might be just as 
astonishing to those who don't read the documentation: -Ofast turns off 
respecting parentheses (and enables *a lot* of optimizations - 
especially those that will make it impossible for the generated code to 
follow any reasonable interpretation of IEEE-754).

Because for my code the latter is not particularly important, I compile 
with -Ofast -fprotect-parens (as it is to be specified with gfortran).

Kind regards,

Toon Moene - e-mail: toon at moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
At home: http://moene.org/~toon/; weather: http://moene.org/~hirlam/
Progress of GNU Fortran: http://gcc.gnu.org/wiki/GFortran#news

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