gfortran and g77 gives different output for same program

[prakash Taksali]

I wrote a sample fortran program for this problem -



Fortran program test.f --



IMPLICIT NONE

REAL*8 X1, Y1, X2, Y2, LENGHT

C READ *, X1, Y1, X2, Y2

X1 = '3FEF6EFA44990F7F'Z

Y1 = '3FEF6EFA44990F7F'Z

X2 = '3FEF6EFA44990F7F'Z

Y2 = '3FEF6EFA44990F7F'Z

WRITE (*,71) , 'LENGHT is ', X1

LENGHT=SQRT((X2-X1)**2 + (Y2-Y1)**2)

PRINT *, 'LENGHT is ', LENGHT

LENGHT=X1 * X2

WRITE (*, 71) , 'LENGHT is ', LENGHT

71 format(1x,a10,2x,z16)

END





Compiled it on ltbbuild (This machine has SUSE linux distribution)
machine like this : g77 test.f

Executed like this :

ptaksali@ltsbuild:~> ./a.out

LENGHT is 3FEF6EFA44990F7F

LENGHT is 0.

LENGHT is 3FEEE085C5257ABB



Compiled it on cpbwbuild (This machine has FC5) machine like this:
gfortran -ff2c test.f

Executed like this :

[ptaksali@cpbwbuild for_prog]$ ./a.out

LENGHT is 43CFF7B77D224C88

LENGHT is 0.00000000000000

LENGHT is 47AFEF711F2A56E7



We can see from above output that same program gives two different
output on different machine.



Pls note that compiler option "-ff2c" does not affect the output.



Can some one from community explain me the reason behind two different
output and how to fix this problem.





Thanks

--Prakash