[Numpy-discussion] f2py NotImplementedError

[Aronne Merrelli]

Hello Andy,

I'm not an expert on f2py, but I've used it in a few cases. I can
recreate a NotImplementedError by copying your commands. The problem
is that you are using -l (lower case L), which I think is supposed to
specify the library name, not a path. The NotImplementedError is not
really what the code should produce in this case, but I don't know
what is going on there.

I think you normally want to use the typical flags, like "-lfoo
-L/path/to/foo" or similar. In any case for this simple example, you
don't really need to use those flags. I can get your code to compile
with this command (I have to specify fcompiler here, otherwise it uses
ifort on my system):

$ gfortran -fPIC -c othermodule.f90 -o othermodule.o
$ f2py --fcompiler=gfortran -m mainmodule -c mainmodule.f90 othermodule.o

This compiles, but then the shared object has no functions in it when
you import it in python. I think that's because your main file is a
program, and I do not think f2py wraps fortran programs, rather only
subroutines/functions. If you change the mainmodule file slightly,
replacing the 'program mains' with:

module mains
  use moderator
contains
  subroutine foo
    ...
  end subroutine foo
end module mains

Compile it similarly, then it looks to work:

$ python -c "import mainmodule ; mainmodule.mains.foo()"
 here's your     1 st number:    2.7182817459106445
 here's your     2 nd number:    3.6945281028747559
 here's your     3 rd number:    3.3475894927978516
 here's your     4 th number:    2.2749228477478027
 here's your     5 th number:    1.2367763519287109
 here's your     6 th number:   0.56031775474548340
 here's your     7 th number:   0.21758595108985901
 here's your     8 th number:    7.3932491242885590E-002
 here's your     9 th number:    2.2329926490783691E-002
 here's your    10 th number:    6.0699032619595528E-003

On Sun, Jul 24, 2016 at 2:54 PM, andy buzza <asbuzza at gmail.com> wrote:
> Hello all,
>
> I have been trying to compile a relatively simple pair of Fortran files, one
> referencing a subroutine from another file (mainmodule.f90 references
> othermodule.f90).  I have been able to compile them using a Fortran
> compiler, but receive a NotImplementedError when using f2py.
>
> Steps I use for f2py:
>
> $gfortran -shared -o othermodule.so othermodule.f90 -fPIC
>
> $f2py -c -l/path/othermodule -m mainmodule mainmodule.f90
>
> I am running this on linux and wasn't sure how to correct the error.
>
> othermodule.f90
>
>   module moderator
>
>     implicit none
>     integer*1 :: i
>     integer*8 :: fact,len
>     real*8,dimension(:),allocatable :: ex
>
>     contains
>
>       subroutine submarine(ii,ff,exex)
>
>         implicit none
>         integer*1 :: ii
>         integer*8 :: ff
>         real*8 :: exex
>
>         exex=exp(real(ii))/ff
>
>       end subroutine submarine
>
>   end module moderator
>
>
> mainmodule.f90
>
>   program mains
>
>     use moderator
>
>     implicit none
>
>     len=10
>     allocate(ex(len))
>     fact=1
>     do i=1,len
>        fact=fact*i
>        call submarine(i,fact,ex(i))
>        if (i==1) then
>           print*,"here's your ",i,"st number: ",ex(i)
>        elseif (i==2) then
>           print*,"here's your ",i,"nd number: ",ex(i)
>        elseif (i==3) then
>           print*,"here's your ",i,"rd number: ",ex(i)
>        else
>           print*,"here's your ",i,"th number: ",ex(i)
>        endif
>     enddo
>     deallocate(ex)
>
>   end program
>
>
> Thanks for the help,
> Andy
>
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