Q117903: FIX: Incorrect Floating-Point Calculations with /Ox and /Op

Article: Q117903
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
========

The program produces incorrect floating-point results when it is compiled using
the /Ox and /Op optimizations (or /Oxp).

RESOLUTION
==========

Do not use both /Ox and /Op when compiling.

STATUS
======

Microsoft has confirmed this to be a bug in FORTRAN PowerStation for MS-DOS,
version 1.0. This problem was corrected in the FORTRAN PowerStation for MS-DOS
maintenance release, version 1.0a.

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

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 the \F32\BIN directory will show version 2.8 for
FORTRAN PowerStation, version 1.0, and will show version 1.0f for the
maintenance release, version 1.0a.

The following sample program can be used to demonstrate this problem. The correct
result is:

  2.929688E-03
  2.929688E-03

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

  C compile options required: /Oxp

     n1 = 1024
     n2 = 512
     c = (1./n1)+(1./n2)
     write (*,*) c
     write (*,*) (1./n1)+(1./n2)
     end

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

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

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