In article <F43Aqt.I3H@midway.uchicago.edu>,
jpgrimes@midway.uchicago.edu (john peter grimes) wrote:
> Hi,
> I just need help with a simple (I htink) problem.
> Basically I am having a bit of trouble understanding the little
> bit of documentation in my idl manuals on call_extern. I just have a f90
> function that I want to call from idl.
Hi John Peter:
I found the IDL example files very confusing. Here is
a straightforward sample of a call_external using a C program to call the
Fortran program.
1) IDL program: idl_ex.pro : Note ALL arrays and variables
defined FIRST in IDL
2) C program: exc.c
3) Fortran program: exf.f
4) make file to compile before running in IDL (Must exit IDL
if you recompile!!!): Make_ex
I have run it on an SGI and IDL 5.0 with Fortran 77. You should be
able to just run the make command (make -f Make_ex) and then run
idl_ex in IDL. I hope it works with Fortran 90. Please let me know. Good
Luck.
Rose
------------------------------------------------------------ -----------------
-- ---idl_ex.pro
------------------------------------------------------------ --
PRO idl_ex
; Define arrays
a_surface = DOUBLE(.19)
sza = DOUBLE(45)
vza= DOUBLE(55)
ra = DOUBLE(65)
nbcloud=14
tau_c = DBLARR(nbcloud)
reflectivity = DBLARR(nbcloud)
print,'before call to external '
result_rtau = CALL_EXTERNAL('exc.so','exc',a_surface,sza,vza,ra, $
tau_c,reflectivity)
print,'Returned value from rtau: ',result_rtau
print,'--------------------Result of CALL_EXTERNAL-----------------------'
print,'tau ',' reflectivity'
FOR k=0,nbcloud-1 DO BEGIN
print,tau_c[k],reflectivity[k]
ENDFOR
end
---exc.c ------------------------------------------------------------ --
/* This program serves as a wrapper for the fortran program exf.f */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
long exc(int argc,void *argv[])
{
extern void exf_();
static int i,j;
static double tau_c[14],reflectivity[14] ;
static double a_surface, sza_deg, vza_deg, ra_deg;
a_surface = *(double *)argv[0];
sza_deg= *(double *)argv[1];
vza_deg= *(double *)argv[2];
ra_deg= *(double *)argv[3];
/* Check to see if values correspond with IDL input */
fprintf(stderr,"%lf %lf %lf %lf \n",a_surface,sza_deg,vza_deg,ra_deg);
fprintf(stderr," -------------Call fortran program----------------- \n");
exf_(&a_surface,&sza_deg,&vza_deg,&ra_deg,ta u_c,reflectivity);
fprintf(stderr,"----------- Returned balues from Fortran: ---------\n");
for (i=0;i<14;++i)
{
*((double *)argv[4] + i) = tau_c[i] ;
*((double *)argv[5] + i) = reflectivity[i] ;
fprintf(stderr," %lf %lf \n",tau_c[i] ,reflectivity[i]);
}
/* Send some strange number as a check to IDL */
return(33);
}
---exf.f ------------------------------------------------------------ --
subroutine exf(albedo,solzen,satzen,phi,tau_c,
6 reflectivity)
integer i
double precision tau_c(14),reflectivity(14)
double precision albedo,solzen,satzen,phi
C Check to see if input values passed correctly
write(*,*)albedo,solzen,satzen,phi
C Calculate new values to be returned to C program and IDL
do 20 i=1,14
tau_c(i) = i*2.0
reflectivity(i) = i/10.
20 continue
return
end
---Make_ex ------------------------------------------------------------ --
LDFLAGS= -lF77 -lU77 -lI77 -lisam -lm OBJS = exc.o exf.o exc : $(OBJS) ld
-shared -o exc.so $(OBJS) $(LDFLAGS) exc.o : exc.c cc -c -KPIC exc.c -o
exc.o exf.o : exf.f f77 -c -KPIC exf.f -o exf.o
------------------------------------------------------------ -----------------
--
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