Fast connection between fortran 77 and 90

[querky]

Hi!

I'm having kind of a "little" problem. I got an old program written in Fortran77 and I want to implement some functionality from Fortran90 routines. The routines are quite long, so I'm not able to rewrite them in F77...

Is there a possibility to connect the routines so that they can communicate (exchange variable values) in a fast way.

I have though about the COMMON Blocks of F77 and the MODULE Statements in F90. Is there a way of connecting these data structures in a way, that a F90 program can read a F77 COMMON Block. (I though about a I/O-interface but I think this is too slow)

Thanks for your help!

 

[eys_physics]

Hey

The connection between Fortran 77 and Fortran 90 is in my opinion a bit tricky. I have myself succeeded to call Fortran 77 subroutines from Fortran 95 (I assume it works in Fortran 90 also) by using the 'call' statement. I have not succeed to call the Fortran 77 functions but I had to rewrite them as subroutines instead. I don't think it is possible to call Fortran 90 code from Fortran 77. To compile the code I think you need a compiler which is able to compile both Fortran 77 and Fortran 90 code, e.g. gfortran
I hope this helps

 

[quicknote]

Hello,

Thank you for reaching out. It is definitely possible to connect Fortran77 and Fortran90 routines in a fast and efficient way. One option is to use the Fortran interoperability features, which allow for data sharing between different versions of Fortran. This can be done using the ISO_C_BINDING module in Fortran90 and the corresponding C interoperability features in Fortran77.

Another option is to use the Fortran interface block, which allows for direct communication between different Fortran routines. This can be achieved by declaring the Fortran77 routines as external subroutines or functions in the Fortran90 code and then calling them as needed.

In terms of the COMMON blocks and MODULE statements, it is possible to use them for data sharing between Fortran77 and Fortran90, but it may require some additional work to ensure compatibility between the two versions. You may need to use the BIND attribute in Fortran90 to ensure that the data structures are compatible with the COMMON blocks in Fortran77.

I hope this helps and good luck with your project!