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Fortran 90 to C

Posted on 2003-10-31
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Last Modified: 2013-11-08
I was perusing the web and found - in effect - source code to convert fortran code to C.  Unfortunately i'm having difficulties  compiling source.

The question.  Does anyone have an f90 to C or f2C (basically a fortran to C converter - preferably fortran 90 to C/C++?) converter that works in a PC enviornment (Unsure how much difference it make, nonetheless, I'm ruinning XP) that I could obtain?  I've got lots of fortran code to convert.

My 'outside' email would be forums_mp@hotmail.com

Thanks in advance
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Question by:forums_mp
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Assisted Solution

by:jkr
jkr earned 100 total points
ID: 9657929
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Author Comment

by:forums_mp
ID: 9658426

Consider the example referenced in the manual for f2c

------------------------------------
FUNCTION DOT(N,X,Y)
INTEGER N
REAL X(N),Y(N)
DOT = 0
DOT 10 I = 1, N
10  DOT = DOT + X(I)*Y(I)
END

using f2c per the above
Error on line 1 of test2.F: illegal continuation card (starts "FUNCTI")
Error on line 2 of test2.F: illegal continuation card (starts "INTEGE")
Error on line 3 of test2.F: illegal continuation card (starts "REAL X")
Error on line 4 of test2.F: nondigit in statement label field "DOT ="
Error on line 5 of test2.F: nondigit in statement label field "DOT 1"
Error on line 4 of test2.F: unclassifiable statement (starts "0")
Error on line 6 of test2.F: labeled continuation line (starts "10  DO")
Error on line 7 of test2.F: nondigit in statement label field "END  "
   MAIN:
Error on line 5 of test2.F: syntax error
Warning on line 7: missing final end statement
------------------------------------------------------------------------
What all this means is beyond me and cant find anything per the documentation highlighting a fix.
Any ideas?

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Accepted Solution

by:
jhance earned 150 total points
ID: 9658938
My how we've forgotten our FORTRAN!!

1) You must start FORTRAN statements in COLUMN 7!  FORTRAN considers column 1 as "special" and you're not following the rules.

2) You must have a final END since you start with a FUNCTION.  This is not really a valid FORTRAN program but it's still translatable.

Starting with the following LEGAL FORTRAN:

      FUNCTION DOT(N,X,Y)
      INTEGER N
      REAL X(N),Y(N)
      DOT = 0
      DO 10 I = 1, N
   10 DOT = DOT + X(I)*Y(I)
      END
      END

I issued the following:

F2C <TEST.F

And the expected response:

/*  -- translated by f2c (version 19970805).
   You must link the resulting object file with the libraries:
      -lf2c -lm   (in that order)
*/

#include "f2c.h"

doublereal dot_(n, x, y)
integer *n;
real *x, *y;
{
    /* System generated locals */
    integer i__1;
    real ret_val;

    /* Local variables */
    static integer i__;

    /* Parameter adjustments */
    --y;
    --x;

    /* Function Body */
    ret_val = (float)0.;
    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
/* L10: */
      ret_val += x[i__] * y[i__];
    }
    return ret_val;
} /* dot_ */
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Expert Comment

by:jhance
ID: 9658941
3) This line:

DOT 10 I = 1, N

is ILLEGAL.  It should be (I assume):

DO 10 I = 1, N
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Author Comment

by:forums_mp
ID: 9660855

Truly appreaciate the timely responses.  I have to apologize, I now have a fotran book.  Simply put i've never used fortran in the past.   with some general clean ups,  I sense this function should look like.

integer *n;
// real *x, *y;
float *x, *y;

float dot_(int *n, float* x, float* y)
{
    /* System generated locals */
    integer i__1;
    // real ret_val;
    float ret_val;

    /* Local variables */
    static integer i__;

    /* Parameter adjustments */
    --y;
    --x;

    /* Function Body */
   //  ret_val = (float)0.;
    ret_val = 0.0;

    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
/* L10: */
     ret_val += x[i__] * y[i__];
    }
    return ret_val;
} /* dot_ */
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Expert Comment

by:jhance
ID: 9661620
BTW, f2c does make C from FORTRAN but the C it makes is NOT very good C.
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