Re: [Numpy-discussion] F2PY cannot see module-scope variables

Jan. 27, 2015

      On 1/26/15, Yuxiang Wang <yw5aj@virginia.edu> wrote:
...
Dear all,
Sorry about being new to both Fortran 90 and f2py.
I have a module in fortran, written as follows, with a module-scope variable
dp:
========================================
! testf2py.f90
module testf2py
    implicit none
    private
    public dp, i1
    integer, parameter :: dp=kind(0.d0)
contains
    real(dp) function i1(m)
        real(dp), intent(in) :: m(3, 3)
        i1 = m(1, 1) + m(2, 2) + m(3, 3)
        return
    end function i1
end module testf2py
========================================
Then, if I run f2py -c testf2py.f90 -m testf2py
It would report an error, stating that dp was not declared.
If I copy the module-scope to the function-scope, it would work.
========================================
! testf2py.f90
module testf2py
    implicit none
    private
    public i1
    integer, parameter :: dp=kind(0.d0)
contains
    real(dp) function i1(m)
        integer, parameter :: dp=kind(0.d0)
        real(dp), intent(in) :: m(3, 3)
        i1 = m(1, 1) + m(2, 2) + m(3, 3)
        return
    end function i1
end module testf2py
========================================
However, this does not look like the best coding practice though, as
it is pretty "wet".
Any ideas?
Thanks,
Shawn
Shawn,

I posted a suggestion as an answer to your question on stackoverflow:
http://stackoverflow.com/questions/28162922/f2py-cannot-see-module-scope-var...

For the mailing-list-only folks, here's what I wrote:

Here's a work-around, in which `dp` is moved to a `types` module, and
the `use types` statement is added to the function `i1`.

    ! testf2py.f90

    module types
        implicit none
        integer, parameter :: dp=kind(0.d0)
    end module types

    module testf2py
        implicit none
        private
        public i1
    contains
        real(dp) function i1(m)
            use types
            real(dp), intent(in) :: m(3, 3)
            i1 = m(1, 1) + m(2, 2) + m(3, 3)
            return
        end function i1
    end module testf2py

In action:

    In [6]: import numpy as np

    In [7]: m = np.array([[10, 20, 30], [40, 50, 60], [70, 80, 90]])

    In [8]: import testf2py

    In [9]: testf2py.testf2py.i1(m)
    Out[9]: 150.0

The change is similar to the third option that I described in this
answer: http://stackoverflow.com/questions/12523524/f2py-specifying-real-precision-i...

Warren
...
--
Yuxiang "Shawn" Wang
Gerling Research Lab
University of Virginia
yw5aj@virginia.edu
+1 (434) 284-0836
https://sites.google.com/a/virginia.edu/yw5aj/
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Re: [Numpy-discussion] F2PY cannot see module-scope variables

Warren Weckesser