INTERFACE operator

[sebastian_gurgul]

Hello,

Can someone tells me what is wrong with this code part ?
It is related to INTERFACE key word.

PROGRAM HELLO
interface
subroutine ddot ()
end subroutine ddot
end interface
call ddot()
END

When I try to compile the source above I get:
/tmp/ifortECzeBy.o(.text+0x21): In function `MAIN__':
: undefined reference to `ddot_'

The source above is a simpler version of sample from Intel Fortran Language Reference document (par.7-8)

Thank you in advance,

[TimP]

If you're intending to link against one of the BLAS-compatible ddot() functions, you will need to make the interface block agree. MKL supplies such interfaces. If you're supplying a different function yourself, why not put it in the same file, and give the compiler a chance to emit more meaningful messages?

Message Edited by tim18 on 04-24-200608:36 AM

[Steven_L_Intel1]

To add to what Tim says, if your intent is to link to a library containing a DDOT routine, you have to name that library in the ifort command that links the application.

[sebastian_gurgul]

All right.
Thank you for help.