[Python] Problem with passing variables between Python and Fortran using F2py

I have been attempting to call a simple Fortran subroutine from python using f2py without success. The Fortran subroutine just adds two numbers defined in the python code. The Fortran code is:

C
SUBROUTINE TESTLIB(A,B,C)
C
REAL, intent (in) :: A, B
REAL, intent (out) :: C
C = A + B
END SUBROUTINE TESTLIB


Python:

import numpy as np
import testlib2

A = 3
B = 2
C = testlib2.testlib(A, B)
print("C = ", C)



I created testlib2.pyd file from the command line with

python -m numpy.f2py -c -m testlib2 testlib2.f


Then placed testlib2.pyd file in the same directory as the python file (testlib.py). I had to install meson, ninja, cmake, charset-normalizer and pkgconfig libraries to make F2py work with Python 3.12.

When I run the python code testlib.py (Spyder 5.5) I receive the following error:

File c:\users\bcn\documents\hps\hps fortran\testlib.py:6
C = testlib2.testlib(A, B)

TypeError: testlib2.testlib() missing required argument 'c' (pos 3).


The call to the Fortran subroutine appears to requiring the C variable to be defined but has been defined as an "out" variable. Not sure why it is doing this. The examples I have seen indicate that the Fortran subroutine needs to have the out variable listed. Using Windows 11 and Python 3.12. Any help would be appreciated. Thanks.

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