Problem converting float -> double complex in f77

[Adam MIROWSKI]

Caspar Terheggen writes about incoherencies in the way f77 treats
complex numbers:
|From:    caspar at wn2.sci.kun.nl (Caspar Terheggen)
|Subject: Problem converting float -> double complex
|
|.....
|Script started on Thu Oct 12 09:30:00 1989
|% more try.f
|      complex*16 z1,z2
|      z1 = 1.0
|      z2 = 1.0/1.0
|      write(*,*) z1,z2
|      end
|% make try
|f77   -sun4 -o try try.f
|try.f:
| MAIN:
|% try
|  (    1.0000000000000,  0.)  (    25.968750000000,  0.)
|% exit
|script done on Thu Oct 12 09:30:20 1989
|
|Why did the conversion to complex*16 go right in one case and wrong in the
|other? I would expect that in both cases a real*4 must be converted to
|complex*16. I am running SunOS 4.0.3_Export #1 on a Sun4. As for the
|compiler: strings /usr/bin/f77 gives (among others) @(#)compile.c 1.70
|88/04/18 SMI.  Any help (e-mail or followup) is appreciated. Thanks in
|advance.

I've studied the question and got following results:
-- FORTRAN 77 doesn't have double precision complex numbers
-- In FORTRAN 77 "*number" can only be appended to CHARACTER
-- By consequence, we are talking about Sun extensions to the standard
-- I have the same results on a Sun4 with the release 3.2EXPORT of
   the system. 'strings /usr/bin/f77 | grep "@(#)"' gives no
   "compile.c" module and the latest date is 87/10/16.
-- The FORTRAN code gives good results on a Sun3 (3.5EXPORT).
   'strings /usr/bin/f77 | grep "@(#)"' gives no "compile.c" module
   and the dates equal to 86/10/07.
-- The code gives good results on MicroSoft FORTRAN Compiler version
   4.01

My impression is that we face a bug in the f77.  My solution is to insert
explicit conversions by CMPLX().  It COULD help, because it helps in the
example above.

Adam Mirowski