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Q108285: FIX: Precision Problem with COMPLEX*16 and /Op

Article: Q108285
Product(s): Microsoft Fortran Compiler
Version(s): 1.0
Operating System(s): 
Keyword(s): 
Last Modified: 24-MAR-2000

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The information in this article applies to:

- Microsoft FORTRAN PowerStation for MS-DOS, version 1.0 
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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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