mixed program c/fortran

**mimi1981** · 08-14-2008

Hi all, I am a beginner in programming in C, C++ as well as fortran.

I am trying to call a fortran subroutine from a c program. I found documentation on how to do that when the arguments of the subroutine are classical, such as integer...but how do you pass a fortran subroutine that has itself a function or another subroutine as an argument to a c program ?

Here is the c code

Code:

 

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "f77.h"


extern "C"{
void LMQN_(int *IERROR, int *N, double X[], double *F, double G[], double W[], int *LW, double *SFUN_, int *MSGLVL
, int *MAXIT, int *MAXFUN, double *ETA, int *STEPMX, double *ACCRCY, double *XTOL);
}


int
main(void)
{
int IERROR,i;
int N=200,LW=4000,MSGLVL,MAXIT,MAXFUN,STEPMX=10;
double F=-1000.0,SFUN_;
double G[300],W[4000],X[300],tipo[300];
double ETA=0.25,ACCRCY=1.0e-15,XTOL;
FILE *inputFPtr;

XTOL=sqrt(ACCRCY);
MAXIT=N/2;
MAXFUN=150*N;


  if((inputFPtr=fopen("conf1_deform.dat","r"))==NULL){
    printf("can't read conf1_deform.dat.dat\n");
    exit(1);
  }


  for(i=0;i<100;i++) {
    fscanf(inputFPtr,"%lf%lf%lf",&tipo[i],&X[i],&X[i+100]);
  }


LMQN_(&IERROR, &N, X, &F, G, W, &LW, SFUN_, &MSGLVL, &MAXIT, &MAXFUN, &ETA, &STEPMX, &ACCRCY, &XTOL);
              
}

Thanks all

Mike

**Salem** · 08-14-2008

You'd have to read the instructions which come with your compiler on how to create mixed-language programs.

**mimi1981** · 08-15-2008

Hi all again, thanks for the answer but has anyone a bit more information to give me on this topic ??

**matsp** · 08-15-2008

Do you mean to say that you want to pass a function pointer to a C function into a fortran function? Or are you passing a fortran function to a C function, or something else?

[I have no idea as to the answer to the question, I'm just attempting to clarify what it is that you want answered, as that would help someone who actually knows the answer].

And I'd also like to make the note that combining languages is always dependant on the compilers involved, so it would be good if you told us what compiler suite(s) you are using.

--
Mats

**mimi1981** · 08-15-2008

Hi,

I will try and clarify.

What I want to do is to include an optimization code from netlib called TN/TNBC in a c code.

The fortran code is working well, the main code is the following.

Code:

an C***********************************************************************
C CUSTOMIZED, NO BOUNDS
C***********************************************************************
C MAIN PROGRAM TO MINIMIZE A FUNCTION (REPRESENTED BY THE ROUTINE SFUN)
C OF N VARIABLES X - CUSTOMIZED VERSION
C
      DOUBLE PRECISION  X(300), F, G(300), W(4000)
      DOUBLE PRECISION  ETA, ACCRCY, XTOL, STEPMX, DSQRT
      EXTERNAL          SFUN
	DOUBLE PRECISION dummy
	integer i
C
C SET UP FUNCTION AND VARIABLE INFORMATION
C N  - NUMBER OF VARIABLES
C X  - INITIAL ESTIMATE OF THE SOLUTION
C F  - ROUGH ESTIMATE OF FUNCTION VALUE AT SOLUTION
C LW - DECLARED LENGTH OF THE ARRAY W
C


        open(33,file="conf1_deform.dat",status='unknown')
        do i=1,100
        read(33,*) dummy,X(i),X(i+100)
        enddo
        close(33)


      N  = 200
!      DO 10 I = 1,N
!         X(I) = I / FLOAT(N+1)
!10    CONTINUE
      F  = 1.D0
      LW = 4000
C
C SET UP CUSTOMIZING PARAMETERS
C ETA    - SEVERITY OF THE LINESEARCH
C MAXFUN - MAXIMUM ALLOWABLE NUMBER OF FUNCTION EVALUATIONS
C XTOL   - DESIRED ACCURACY FOR THE SOLUTION X*
C STEPMX - MAXIMUM ALLOWABLE STEP IN THE LINESEARCH
C ACCRCY - ACCURACY OF COMPUTED FUNCTION VALUES
C MSGLVL - DETERMINES QUANTITY OF PRINTED OUTPUT
C          0 = NONE, 1 = ONE LINE PER MAJOR ITERATION.
C MAXIT  - MAXIMUM NUMBER OF INNER ITERATIONS PER STEP
C
      MAXIT  = N/2
      MAXFUN = 150*N
      ETA    = .25D0
      STEPMX = 1.D1
      ACCRCY = 1.D-15
      XTOL   = DSQRT(ACCRCY)
      MSGLVL = 1
C
C MINIMIZE THE FUNCTION
C
      CALL LMQN (IERROR, N, X, F, G, W, LW, SFUN,
     *     MSGLVL, MAXIT, MAXFUN, ETA, STEPMX, ACCRCY, XTOL)
C
C PRINT THE RESULTS
C
      IF (IERROR .NE. 0) WRITE(*,800) IERROR
      IF (MSGLVL .GE. 1) WRITE(*,810)
      IF (MSGLVL .GE. 1) WRITE(*,820) (I,X(I),I=1,N)
      STOP
800   FORMAT(//,' ERROR CODE =', I3,/)
810   FORMAT(10X, 'CURRENT SOLUTION IS ',/14X, 'I', 11X, 'X(I)')
820   FORMAT(10X, I5, 2X, 1PD22.15)
      END
C
C

      SUBROUTINE SFUN (N, X, F, G)
      DOUBLE PRECISION  X(N), G(N), F, T
	integer i,j
   	DOUBLE PRECISION  Vp,v,cutoff,pot_cutoff,dx,dy,r2
        DOUBLE PRECISION  sigma_xy,Fx,Fy,r(100)


	open(33,file="conf1_deform.dat",status='unknown')
	do i=1,100
	read(33,*) r(i)
	enddo
	close(33)

	v=0.d0
	F = 0.D0
	do i=1,100
	G(i) = 0.d0
	G(i+100) = 0.d0
	enddo

	do i=1,100
	 do j=1,100
	 if (i.ne.j) then
	 sigma_xy=(r(i)+r(j))/2.d0
	 cutoff=2.d0**(7.d0/6.d0)*sigma_xy
	 pot_cutoff=4*((sigma_xy*sigma_xy/(cutoff*cutoff))**6.d0-
     $        (sigma_xy*sigma_xy/(cutoff*cutoff))**3.d0)
	 dx=X(i)-X(j)
	 dy=X(i+100)-X(j+100)
	 if (dx.ge.10.3975/2.d0) dx=dx-10.3975
	 if (dx.le.-10.3975/2.d0) dx=dx+10.3975
	 if (dy.ge.10.3975/2.d0) dy=dy-10.3975
         if (dy.le.-10.3975/2.d0) dy=dy+10.3975

	 r2=dx*dx+dy*dy

	 if (r2.le.cutoff*cutoff) then
	 Vp=4*((sigma_xy*sigma_xy/r2)**6-(sigma_xy*sigma_xy/r2)**3)-pot_cutoff
!	 print *, i, j, Vp
	 F=F+Vp/2.0

	 Fx=48.d0*sigma_xy**12.d0*dx/r2**7.d0-
     $    24.d0*sigma_xy**6.d0*dx/r2**4.d0
	 Fy=48.d0*sigma_xy**12.d0*dy/r2**7.d0-
     $    24.d0*sigma_xy**6.d0*dy/r2**4.d0
	 G(i) =  G(i) - Fx
	 G(i+100) = G(i+100) - Fy	  
	 endif
	 
	 endif
 	 enddo
	enddo	



C
C ROUTINE TO EVALUATE FUNCTION (F) AND GRADIENT (G) OF THE OBJECTIVE
C FUNCTION AT THE POINT X
C

!      F = 0.D0
!      DO 10 I = 1,N
!         T    = 2*X(I) - I
!         F    = F + T*T
!         G(I) = 2.D0 * T
!10    CONTINUE
 
!     RETURN

      END

The previous code I posted a c code is aimed at doing the same thing. This is just a test later I will call the subroutine LMQN from another c code that I am using. My difficulty is that I DON'T KNOW HOW TO CALL A SUBROUTINE FROM C (LMQN) THAT HAS AS ARGUMENT ANOTHER SUBROUTINE (SFUN).

Thank you for your help.
If there are references on this, please let me know.

To compile my c codes I use gcc or g++.

Mike

**matsp** · 08-15-2008

Ok, and are you using g77 to compile your fortran?

Have you tried declaring SFUN() in your C code:

Code:

extern "C" void  SFUN _(int *N, double *X, double *F, double *G);

[I'm not 100% sure that's the right format, but something along those lines].

--
Mats

**mimi1981** · 08-15-2008

Hi I really appreciate your help.

I use this syntax

Code:

extern "C"{
void SFUN_(int *N, double X[], double *F, double G[]);
}

I compile in this way

g++ -c minim.c
ifort -c tn.f blas.f sfun.f
g++ minim.o tn.o blas.o sfun.o

and I get this error message (I cut it as it goes on and on)

/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« tn.o Â» est incompatible avec la sortie i386:x86-64
/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« blas.o Â» est incompatible avec la sortie i386:x86-64
/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« sfun.o Â» est incompatible avec la sortie i386:x86-64
minim.o(.text+0x1d6): In function `main':
: undefined reference to `LMQN_'
tn.o(.text+0x136): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x16d): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x1a1): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x1d7): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x204): In function `tn_':
: undefined reference to `for_write_seq_fmt_xmit'

My problem is how to pass the subroutine SFUN_ as an argument inside the other subroutine LMQN_.

For the moment I passing like that

Code:

extern "C"{
void LMQN_(int *IERROR, int *N, double X[], double *F, double G[], double W[], int *LW, void *SFUN_, int *MSGLVL, int *MAXIT, int *MAXFUN, double *ETA, int *STEPMX, double *ACCRCY, double *XTOL);
}

and

Code:

LMQN_(&IERROR, &N, X, &F, G, W, &LW, &SFUN_, &MSGLVL, &MAXIT, &MAXFUN, &ETA, &STEPMX, &ACCRCY, &XTOL);

Thanks for the suggestion any other ideas ???

**matsp** · 08-15-2008

First of all, "architecture i386 du fichier d'entrÃ©e Â« tn.o Â» est incompatible avec la sortie i386:x86-64" says that your file contains x86_32 functions, so you should pass -m32 to g++ to match the functions to your C++ code.

This would be a more correct version of passing SFUN_ to your function.

Code:

void LMQN_(int *IERROR, int *N, double X[], double *F, double G[], double W[], int *LW, void (*SFUN_)(int *N, double X[], double *F, double G[]), int *MSGLVL, int *MAXIT, int *MAXFUN, double *ETA, int *STEPMX, double *ACCRCY, double *XTOL);

--
Mats

**mimi1981** · 08-15-2008

This makes more sence.

Here is what I get now.

g++ -c minim.c -m32

minim.c: In function `int main()':
minim.c:45: erreur: ne peut convertir Â« double Â» Ã Â« void (*)(int*, double*, double*, double*) Â» pour l'argument Â« 8 Â» vers Â« void LMQN_(int*, int*, double*, double*, double*, double*, int*, void (*)(int*, double*, double*, double*), int*, int*, int*, double*, int*, double*, double*) Â»

(sorry for all this french)

You didn't mention how I should pass the subroutine SFUN_ as an argument when I call LMQN_ in the c code. For the moment I am doing

Code:

LMQN_(&IERROR, &N, X, &F, G, W, &LW, SFUN_, &MSGLVL, &MAXIT, &MAXFUN, &ETA, &STEPMX, &ACCRCY, &XTOL);

I also tried &SFUN_ and it gives the above error.
What is the proper syntax ?

By the way do you know any usefull reference on these topics?

Thanks a lot.

Mike

**matsp** · 08-15-2008

Trying to read the french and translating to English, I get the impression that it says that it can't translate a double to void (*)(...) for argument 8 - which seems strange to me.

No, I don't know of any references for this.

--
Mats

**mimi1981** · 08-15-2008

ANY SPECIALIST ON HOW TO MIX THE LANGUAGES FORTRAN AND C see threads above???

Thanks I am stuck there for 5 days and I suspect it is trivial.

Thanks everyone and Mats especially.

**matsp** · 08-15-2008

Originally Posted by mimi1981

ANY SPECIALIST ON HOW TO MIX THE LANGUAGES FORTRAN AND C see threads above???

Thanks I am stuck there for 5 days and I suspect it is trivial.

Thanks everyone and Mats especially.

Just to clarify, the current problem is a pure C (or C++) problem, not a Fortran mix with C++ problem - or at least, the compiler error should be solved with fixing the C++ code, it may not be completely correct in other ways, and that may cause problems in the interface, but at the moment, it's a pure C++ problem.

Can you post the whole C++ code as it stands now?

--
Mats

**mimi1981** · 08-15-2008

Here is the code (with my question in red).

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "f77.h"     [COLOR="I don't know what this does ?"][/COLOR]


extern "C"{
void SFUN_(int *N, double X[], double *F, double G[]);
}


//extern "C" void  SFUN_(int *N, double *X, double *F, double *G);

extern "C"{
void LMQN_(int *IERROR, int *N, double X[], double *F, double G[], double W[], int *LW, void (*SFUN_)(int *N, doub
le X[], double *F, double G[]), int *MSGLVL, int *MAXIT, int *MAXFUN, double *ETA, int *STEPMX, double *ACCRCY, do
uble *XTOL);
}


int
main(void)
{
int IERROR,i;
int N=200,LW=4000,MSGLVL,MAXIT,MAXFUN,STEPMX=10;
double F=-1000.0,SFUN_;
double G[300],W[4000],X[300],tipo[300];
double ETA=0.25,ACCRCY=1.0e-15,XTOL;
FILE *inputFPtr;

XTOL=sqrt(ACCRCY);
MAXIT=N/2;
MAXFUN=150*N;


  if((inputFPtr=fopen("conf1_deform.dat","r"))==NULL){
    printf("can't read conf1_deform.dat.dat\n");
    exit(1);
  }


  for(i=0;i<100;i++) {
    fscanf(inputFPtr,"%lf%lf%lf",&tipo[i],&X[i],&X[i+100]); [COLOR="How could I pass tipo[i] to the function SFUN without changing its signature ie the number of its arguments ???"][/COLOR]
  }


LMQN_(&IERROR, &N, X, &F, G, W, &LW, &SFUN_, &MSGLVL, &MAXIT, &MAXFUN, &ETA, &STEPMX, &ACCRCY, &XTOL); [COLOR="WHAT SHOULD I TYPE THERE &SFUN_, SFUN...?????"][/COLOR]



}

The function sfun.f is the following

Code:

      SUBROUTINE SFUN (N, X, F, G)
      DOUBLE PRECISION  X(N), G(N), F, T
        integer i,j
        DOUBLE PRECISION  Vp,v,cutoff,pot_cutoff,dx,dy,r2
        DOUBLE PRECISION  sigma_xy,Fx,Fy,r(100)


        open(33,file="conf1_deform.dat",status='unknown')
        do i=1,100
        read(33,*) r(i)
        enddo
        close(33)

        v=0.d0
        F = 0.D0
        do i=1,100
        G(i) = 0.d0
        G(i+100) = 0.d0
        enddo

        do i=1,100
         do j=1,100
         if (i.ne.j) then
         sigma_xy=(r(i)+r(j))/2.d0
         cutoff=2.d0**(7.d0/6.d0)*sigma_xy
         pot_cutoff=4*((sigma_xy*sigma_xy/(cutoff*cutoff))**6.d0-
     $        (sigma_xy*sigma_xy/(cutoff*cutoff))**3.d0)
         dx=X(i)-X(j)
         dy=X(i+100)-X(j+100)
         if (dx.ge.10.3975/2.d0) dx=dx-10.3975
         if (dx.le.-10.3975/2.d0) dx=dx+10.3975
         if (dy.ge.10.3975/2.d0) dy=dy-10.3975
         if (dy.le.-10.3975/2.d0) dy=dy+10.3975

         r2=dx*dx+dy*dy

         if (r2.le.cutoff*cutoff) then
         Vp=4*((sigma_xy*sigma_xy/r2)**6-(sigma_xy*sigma_xy/r2)**3)-pot_cutoff
!        print *, i, j, Vp
         F=F+Vp/2.0

         Fx=48.d0*sigma_xy**12.d0*dx/r2**7.d0-
     $    24.d0*sigma_xy**6.d0*dx/r2**4.d0
         Fy=48.d0*sigma_xy**12.d0*dy/r2**7.d0-
     $    24.d0*sigma_xy**6.d0*dy/r2**4.d0
         G(i) =  G(i) - Fx
         G(i+100) = G(i+100) - Fy
         endif

         endif
         enddo
        enddo


      END

and F77.h is (I found that on the internet maybe it does not make sense to put it as an include ?????

Code:

#ifndef Lib_F77_h
#define Lib_F77_h

#ifdef WIN32
#define Lib_stdcall __stdcall
#else
#define Lib_stdcall
#endif

#endif

THANKS A LOT

**matsp** · 08-15-2008

It was probably in your original code, but changing this line:

Code:

double F=-1000.0,SFUN_;

into

Code:

double F=-1000.0;

makes the code compile with g++ on my machine. It doesn't link because I don't have the libraries. And there may of course be other problems.

As to how you pass "tipo[i]", I think you would not do that, since sfun() reads that from the datafile in itself.

If you want to read the file only once, you would have to change the FORTRAN code around to take another argument double tipo[] in both LMQN and SFUN, and pass tipo from LMQN to SFUN.

--
Mats

**mimi1981** · 08-15-2008

So that is one stupid mistake sorted. Thanks and sorry about that.

One question you haven't answered is how to pass SFUN as an argument to the function LMPQ when I call it through

Code:

LMQN_(&IERROR, &N, X, &F, G, W, &LW, &SFUN_, &MSGLVL, &MAXIT, &MAXFUN, &ETA, &STEPMX, &ACCRCY, &XTOL);

Is this the right syntax ?? or is it something else SFUN_,SFUN ....??

If this is correct, I think we are back to the initial questions about the way to link C++ and fortran functions.

I do

g++ -c minim.c -m32
ifort -c tn.f
ifort -c blas.f
ifort -c sfun.f
g++ minim.o blas.o sfun.o tn.o -m32

and I get the horrible
/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« minim.o Â» est incompatible avec la sortie i386:x86-64
/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« tn.o Â» est incompatible avec la sortie i386:x86-64
/usr/bin/ld: AVERTISSEMENT: architecture i386 du fichier d'entrÃ©e Â« sfun.o Â» est incompatible avec la sortie i386:x86-64
minim.o(.text+0x169): In function `main':
: undefined reference to `SFUN_'
minim.o(.text+0x1a7): In function `main':
: undefined reference to `LMQN_'
tn.o(.text+0x136): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x16d): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x1a1): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x1d7): In function `tn_':
: undefined reference to `for_write_seq_fmt'
tn.o(.text+0x204): In function `tn_':
: undefined reference to `for_write_seq_fmt_xmit'
tn.o(.text+0x226): In function `tn_':
: undefined reference to `for_write_seq_fmt_xmit'
tn.o(.text+0x241): In function `tn_':
: undefined reference to `for_write_seq_fmt_xmit'
tn.o(.text+0x2bd): In function `lmqn_.':

and on and on....

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