[Numpy-discussion] Attempting to wrap a Fortran-77 subroutine using f2py but I haven't been able to understand what is causing the error

[Melissa Mendonça]

The documentation for f2py is not very complete, I'm afraid. I'll try to
work on that front in the next few months. For now, you can find it here:
https://numpy.org/doc/stable/f2py

Cheers,

Melissa

On Mon, Oct 19, 2020 at 2:35 PM Samuel Dupree <sdupree at speakeasy.net> wrote:

> One more question. Where can I find a documentation on f2py that covers
> issues like assumed shaped arrays, and issues such as the one discussed in
> this post?
>
> Sam Dupree.
>
>
> On October/19/2020 13:01:13, Melissa Mendonça wrote:
>
> Sure, you can use assume-shape arrays, but if you generate a signature
> file using
>
> $ f2py rkfn78.for -m rkfn78 -h rkfn78.pyf
>
> you can see that f2py correctly determines n to be the length of the array
> Y, but since YP also depends on n, that's what generated the error you saw
> the first time.
>
> If you change the .pyf signature file to the one attached to this message,
> delete your original cf2py lines in the .for file and compile it all using
>
> $ f2py -c rkfn78.pyf rkfn78.for --fcompiler=gfortran --f77flags="-c -O
> -Wall" -m rkfn78
>
> then you'll have no trouble with assumed-shape arrays.
>
> Cheers,
>
> Melissa
>
> On Mon, Oct 19, 2020 at 1:03 PM Samuel Dupree <sdupree at speakeasy.net>
> wrote:
> >
> > Melissa,
> >
> > Thank you for answering my post. I made the changes you recommended and
> the code compiles successfully. But I do have one question. The arrays
> being passed in the CALL to FCN were treated as assumed shaped arrays in
> the called subroutine. Are assumed shaped arrays a problem for f2py?
> >
> > Sam Dupree.
> >
> >
> > On October/19/2020 09:16:02, Melissa Mendonça wrote:
> >
> > Hello, Sam, sorry for taking so long to answer!
> >
> > The problem seems to be that you are using
> >
> > cf2py depend(in) Y, YP
> >
> > instead of
> >
> > cf2py depend(n) Y, YP <- (note that there was a spurious i in that
> depend expression)
> >
> > and that the callback FCN needs the dimension n as an argument. I was
> able to compile your code correctly after making these changes.
> >
> > If you have any further questions let me know, I hope this helps.
> >
> > Cheers,
> >
> > Melissa
> >
> >
> > On Wed, Oct 14, 2020 at 4:03 AM Samuel Dupree <sdupree at speakeasy.net>
> wrote:
> >>
> >> I'm attempting to wrap a Fortran-77 source member using f2py. I'm
> >> running he Anaconda distribution for Python 3.7.6 on a Mac Pro (2019)
> >> under Mac OS X Catalina (ver. 10.15.6). The version of NumPy I'm running
> >> is 1.18.3.
> >>
> >> I've attached a copy of the Fortran source code to this note (see
> >> rkfn78.for). The command I'm using to wrap this code is
> >>
> >> f2py3 -c rkfn78.for --fcompiler=gfortran --f77flags="-c -O -Wall" -m
> rkfn78
> >>
> >> The output I get is captured in the file rkfn78_build_output.txt.
> >>
> >> I don't understand the cause behind the error message I get, so any
> >> advice would be welcomed.
> >>
> >> Sam Dupree.
> >> _______________________________________________
> >> NumPy-Discussion mailing list
> >> NumPy-Discussion at python.org
> >> https://mail.python.org/mailman/listinfo/numpy-discussion
> >
> >
> > _______________________________________________
> > NumPy-Discussion mailing list
> > NumPy-Discussion at python.org
> > https://mail.python.org/mailman/listinfo/numpy-discussion
> >
>
>
>
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