Re: ELEMENTAL functions and performance

On Jul 29, 12:57 pm, deltaquattro <deltaquat...@xxxxxxxxx> wrote:
Hi,

I would like to know if the attribute ELEMENTAL for a function/
subroutine can negatively affect performance or not.

I am going to code a lot of small functions, for things like Jacobi
polynomial evalution, Gauss point generation, etc. etc., to be used in
a "huge" code. I would like the functions to work for scalar as well
as for rank-1 array input/output. I'd prefer to write them as
ELEMENTAL, rather than forcing the user to read/write a scalar into a
rank-1 array of size 1 each time he has to use the subroutine for
scalars.
However, sometimes I heard that some "new" features of the language
may have an hit on performance, because they make optimization more
difficult for the compiler. I don't know if this is the case with
ELEMENTAL, however these functions will be called a lot of times, so
it's not a good idea if they are slow. The code will run on parallel
vectorial supercomputers. According to these informations, what would
you suggest me to do?
Thanks,

Best Regards,

deltaquattro

I think one the purpose of having elemental functions was that
compilers can optimize it better (for example by auto-parallelization
when used on whole arrays). What they actually do in practice is a
different matter alltogether.
.

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