Re: How to call fortran subroution?

["L. Paul Mix" <lpmix(at)sandia.gov>]

web wrote:

Thank you very much. I use IDL under windows.

I have generated vecadd.dll from visual fortran. Then I use

result = call_external('f:\fortran\vecadd.dll','f:\fortran\vecadd ',  a,
n_elements(a), x, n_elements(x), b)

to call the dll. The error message is as following:

% CALL_EXTERNAL: Error loading sharable executable.
                 Symbol: f:\fortran\vecadd, File = f:\fortran\vecadd.dll
                 ERROR_PROC_NOT_FOUND
But I have dll file under f:\fortran. How to do then? May be I have set
wrong parameter.
This is explanation of call_external:

Result = CALL_EXTERNAL(Image, Entry [, P0, ..., PN-1])

Entry:A string containing the name of the symbol in the library which is the
entry point of the routine to be called.

I donot know how to set entry.

Where can I find The IDL External Development Guide?

Jiali

"Liam Gumley" <Liam.Gumley@ssec.wisc.edu> wrote in message

<Deleted>
For windows with Compaq (Digital) Fortran add the export line to your
wrapper subroutine:
      subroutine wvecadd (argc, argv)
cDEC$ ATTRIBUTES DLLEXPORT :: wvecadd
      integer argc, argv(*)
      call vecadd(%val(argv(1)), %val(argv(2)),
%val(argv(3)), %val(argv(4)))
      return
      end

When you call:
junk = call_external('f:\fortran\vecadd.dll', '_WVECADD@8', p1, p2, p3, p4)

Note the @8 refers to the fact that two pointers are passed to wvecadd for a total of 8 bytes.  The syntax of Call_External makes this suffix true for all Call_external calls on windows.

Note on HP and Sun unix the entries are 'wvecadd' and 'wvecadd_', respectively. You will need to branch if you are writing these routines form multiple platforms.

Good luck.
 
 

-- 
L. Paul Mix
Distinguished Member of the Technical Staff
Electromagnetics and Plasma Physics Analysis

Sandia National Laboratories
MS 1152, P.O. Box 5800
Albuquerque, NM 87185-1152
E-mail: lpmix@sandia.gov
Phone: (505) 845-7493
FAX: (505) 284-6078