f2py error: undefined symbol

Question

I need to wrap a simply fortran90 code with f2py. The fortran module "test.f90" is

module util

contains

FUNCTION gasdev(idum)
implicit none
INTEGER(kind=4), intent(inout) :: idum
REAL(kind=8) :: gasdev, ran2
print*,idum
gasdev = ran2(idum)
return
END FUNCTION

FUNCTION ran2(idum)
implicit none
INTEGER(kind=4), intent(inout) :: idum
REAL(kind=8) :: ran2
print*,idum
ran2=2.D0
return
END FUNCTION
end module util

and then I wrap it with

f2py  -m test -c test.f90

but when I import it in python

In [2]: import test

it prompted me with error saying

ImportError: ./test.so: undefined symbol: ran2_

Any ideas on how to fix it? Thanks.

Answer 1

In function gasdev you declare ran2 as an external function. As you then don't link in any such function importing the module will fail.

Instead, remove the declaration of ran2 in gasdev, in which case the ran2 call uses the explicit interface to the ran2 function in the module, and everything works.