DOCUMENT:Q108285  24-MAR-2000  [fortran]
TITLE   :FIX: Precision Problem with COMPLEX*16 and /Op
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft FORTRAN PowerStation for MS-DOS, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

A program, compiled with the /Op option that contains double precision COMPLEX
arithmetic may produce only a single precision result.

CAUSE
=====

When optimizing for precision, the compiler always stores intermediate results
of equations in memory locations rather than leaving the results on the
coprocessor stack. The problem occurs because the COMPLEX*16 intermediate
results are incorrectly stored in 8-byte memory locations.

RESOLUTION
==========

Do not compile routines that perform COMPLEX*16 arithmetic with /Op.

STATUS
======

Microsoft has confirmed this to be a problem in FORTRAN PowerStation version 1.0
for MS-DOS. This problem has been resolved with FORTRAN PowerStation maintenance
release version 1.0a for MS-DOS.

FORTRAN PowerStation version 1.0 can be differentiated from the maintenance
release version 1.0a by invoking the linker. Typing "link32 | more" (without the
quotation marks) from \F32\BIN directory will show version 2.8 for FORTRAN
PowerStation version 1.0, and it will show version 1.0f for the maintenance
release version 1.0a.

MORE INFORMATION
================

The following sample demonstrates the problem under FORTRAN PowerStation 1.0
when compiled with /Op:

Sample Code
-----------

   c Compile options required: /Op
         COMPLEX*16 A,B,C
         REAL*8     D,E,F
         DATA A / (1.d0,0.d0) / 
         DATA B / (.3d0,0.d0) / 

         C = A/B
         D = REAL(A)
         E = REAL(B)
         F = D/E
         PRINT *,'C=',C
         PRINT *,'F=',F
         END

Additional query words: 1.00 1.00a buglist1.00 fixlist1.00a

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword3 kbFORTRANPower100DOS
Version           : :1.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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