[petsc-users] [Fortran] subroutines inside modules?

[Leo van Kampenhout]

Thank you Stephan, it is working now. I forgot to add the correct files to
the makefile, for I put the module in a seperate file (grid.F). The correct
makefile rule for the main program (main.F) is:

main: grid.o main.o chkopts
    -${FLINKER} -o main grid.o main.o ${PETSC_KSP_LIB}
    ${RM} main.o grid.o

Thanks again.

Leo


2010/10/1 Stephan Kramer <s.kramer at imperial.ac.uk>

> On 30/09/10 23:09, Leo van Kampenhout wrote:
>
>> Declaring it external in the program/subroutine that is using the module
>> results in
>>
>> main.F:65.43:
>>       external gridtest
>> Error: Cannot change attributes of USE-associated symbol at (1)
>>
>> Thanks, Leo
>>
>
> Yes, as I said before :) - module subroutines should *not* be declared
> external. You do
> not need that line.
>
> Cheers
> Stephan
>
>
>
>>
>> 2010/9/30 Stephan Kramer <s.kramer at imperial.ac.uk
>> <mailto:s.kramer at imperial.ac.uk>>
>>
>>
>>    On 30/09/10 15:31, Leo van Kampenhout wrote:
>>
>>        Hi all,
>>
>>        since it is mandatory to declare all subroutines as "external" in
>>        Fortran, is it possible for Modules to have subroutines? I'm
>>        unable to
>>        declare the subroutine external inside the module itself, nor in
>> the
>>        program which is using it. Not declaring it external at all
>>        results in
>>        the following compilation error:
>>
>>        /net/users/csg/csg4035/master/workdir/src/main.F:97: undefined
>>        reference
>>        to `__grid_MOD_readgrid'
>>
>>        (the module is here is named "grid", the subroutine "readgrid" )
>>
>>        Thanks,
>>        Leo
>>
>>
>>    If you put your subroutine in a module, it should not be declared
>>    external. You can directly call it from within the module itself. When
>>    calling it inside any other module/program you need to add "use
>>    grid" before
>>    the "implicit none".
>>
>>    Putting subroutines inside a module is highly recommended as it
>>    automatically
>>    provides an explicit interface so that the compiler can check the
>>    arguments in
>>    your subroutine call.
>>
>>    Cheers
>>    Stephan
>>
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101001/603fe1cd/attachment-0001.htm>