Fortran subroutine called from Objective-C

Fortran subroutine called from Objective-C

I am calling a fortran subroutine from a cocoa application. The
application is building with success and working as expected but I have
this semantic issue : Implicit declaration of function is invalid in C99
This is a link to the code : [Screen shot]
![https://files.zonge.com/public.php?service=files&t=09f6bf66577d130328b9514ebb7da133&download]
What am I doing wrong ? Thank you for your help.