compiler flag question

Hi

How can I make my code do something depending on my compiler flag?
For example, if I use the -openmp flag I want a loop to have a
different range.

i.e.

if (flag -openmp)
do i=1,10
else
do i=1,5
endif

do loop

enddo

Thanks

tomguest@hotmail.com wrote:
> Hi
>
> How can I make my code do something depending on my compiler flag?
> For example, if I use the -openmp flag I want a loop to have a
> different range.
>
> i.e.
>
> if (flag -openmp)
> do i=1,10
> else
> do i=1,5
> endif
>
> do loop
>
> enddo

You can find examples on the use of
#ifdef _OPENMP
by a simple web search.

cheers for the help.

tomguest@hotmail.com wrote:

> How can I make my code do something depending on my compiler flag?
> For example, if I use the -openmp flag I want a loop to have a
> different range.

> if (flag -openmp)
> do i=1,10
> else
> do i=1,5
> endif

You can't do that in Fortran, or pretty much any
compiled language. (I have seen it done in BASIC).

But you say compiler flag. If you use the C preprocessor,
you can do

#ifdef OPENMP
do i=1,10
#else
do i=1,5
#endif

where OPENMP is a preprocessor symbol, defined either
with #define, or a compiler option such is -DOPENMP

At compile time, one or the other will be compiled.

-- glen

On Wed, 20 Aug 2008 12:42:03 -0800, glen herrmannsfeldt posted:

> tomguest@hotmail.com wrote:
>
>> How can I make my code do something depending on my compiler flag?
>> For example, if I use the -openmp flag I want a loop to have a
>> different range.
>
>> if (flag -openmp)
>> do i=1,10
>> else
>> do i=1,5
>> endif
>
> You can't do that in Fortran, or pretty much any
> compiled language. (I have seen it done in BASIC).
>
> But you say compiler flag. If you use the C preprocessor,
> you can do
>
> #ifdef OPENMP
> do i=1,10
> #else
> do i=1,5
> #endif
>
> where OPENMP is a preprocessor symbol, defined either
> with #define, or a compiler option such is -DOPENMP
>
> At compile time, one or the other will be compiled.
>
> -- glen

Yikes. You can do that with C, but would you?
--
Wealth - any income that is at least one hundred dollars more a year than
the income of one's wife's sister's husband. 6
H. L. Mencken

On Aug 20, 8:37*pm, tomgu...@hotmail.com wrote:
> Hi
>
> How can I make my code do something depending on my compiler flag?
> For example, if I use the -openmp flag I want a loop to have a
> different range.
>
> i.e.
>
> if (flag -openmp)
> * do i=1,10
> else
> * do i=1,5
> endif
>
> do loop
>
> enddo
>
> Thanks

If machine dependent, use
#ifdef _OPENMP
call sub_openmp ( parms )
#else
call sub_other (parms )
#endif

On 21 aug, 03:23, Ron Ford <r...@example.invalid> wrote:
> On Wed, 20 Aug 2008 12:42:03 -0800, glen herrmannsfeldt posted:
>
>
>
>
>
> > tomgu...@hotmail.com wrote:
>
> >> How can I make my code do something depending on my compiler flag?
> >> For example, if I use the -openmp flag I want a loop to have a
> >> different range.
>
> >> if (flag -openmp)
> >> * do i=1,10
> >> else
> >> * do i=1,5
> >> endif
>
> > You can't do that in Fortran, or pretty much any
> > compiled language. *(I have seen it done in BASIC).
>
> > But you say compiler flag. *If you use the C preprocessor,
> > you can do
>
> > #ifdef OPENMP
> > * * do i=1,10
> > #else
> > * * do i=1,5
> > #endif
>
> > where OPENMP is a preprocessor symbol, defined either
> > with #define, or a compiler option such is -DOPENMP
>
> > At compile time, one or the other will be compiled.
>
> > -- glen
>
> Yikes. *You can do that with C, but would you?
> --
> Wealth - any income that is at least one hundred dollars more a year than
> the income of one's wife's sister's husband. 6
> H. L. Mencken- Tekst uit oorspronkelijk bericht niet weergeven -
>
> - Tekst uit oorspronkelijk bericht weergeven -

You can use COCO if you want a Fortran-only solution

Regards,

Arjen

On 20 aug, 14:37, tomgu...@hotmail.com wrote:
> Hi
>
> How can I make my code do something depending on my compiler flag?
> For example, if I use the -openmp flag I want a loop to have a
> different range.
>
> i.e.
>
> if (flag -openmp)
> * do i=1,10
> else
> * do i=1,5
> endif
>
> do loop
>
> enddo
>
> Thanks

Out of curiosity: why is the loop different if you use OpenMP
than if you don't - especially as this is a compile-time
decision, not part of the input for the problem.

Regards,

Arjen

How about

imax = 5
!$ imax = 10
do i=1, imax
:
end do

Regards

tomguest@hotmail.com schrieb:
> Hi
>
> How can I make my code do something depending on my compiler flag?
> For example, if I use the -openmp flag I want a loop to have a
> different range.
>
> i.e.
>
> if (flag -openmp)
> do i=1,10
> else
> do i=1,5
> endif
>
> do loop
>
> enddo
>
> Thanks

I basically want to have different output to certain files depending
on how the user compiles the code.

I just gave the loop problem as an example. I'm also incorporating
some other features that I want to enable by compiler flags.