[petsc-dev] the complex dot business

[Alexander Grayver]

On 27.02.2012 18:01, Matthew Knepley wrote:
> On Mon, Feb 27, 2012 at 10:55 AM, Barry Smith <bsmith at mcs.anl.gov 
> <mailto:bsmith at mcs.anl.gov>> wrote:
>
>
>       I'm afraid the sudden appearance of the blas dot for complex
>     numbers problem is my fault.
>
>       Traditionally since 199x we never used the complex dot product
>     from blas because of the return complex type problem. VecDot_Seq()
>     used #ifdef for complex and a simple loop.
>
>       Since some blas norm suck I off-hand told Shri to use dot for
>     norm and wasn't thinking the complex case.
>
>       Since then, of course, the complex dot problem has been coming up.
>
>       Maybe it is best to continue to never use complex blas dot and
>     just change the VecNorm_ routines to use norm for complex and not
>     dot.? Just throw away this silly problem and time sink?
>
>
> Why is this such a problem? Just use PetscScalar for the BLASdot_() 
> return type and its fine.

For instance MKL's BLAS returns result for zdot in the first argument 
and PETSc's BLASdot_() fails there.

>
>    Matt
>
>
>        Barry
>
>
>
>
> -- 
> What most experimenters take for granted before they begin their 
> experiments is infinitely more interesting than any results to which 
> their experiments lead.
> -- Norbert Wiener


-- 
Regards,
Alexander

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