DOCUMENT:Q150134  02-NOV-1999  [fortran]
TITLE   :BUG: FOR4165 Warning Underflow of Smallest Positive REAL*8
PRODUCT :Microsoft Fortran Compiler
PROD/VER::4.0
OPER/SYS:
KEYWORDS:kbFortranPS kbLangFortrankbbuglist

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The information in this article applies to:

 - Microsoft Fortran PowerStation for Windows 95 and Windows NT, version 4.0 
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SYMPTOMS
========

Compiling a source file that contains an assignment of the smallest positive
REAL*8 literal constant to a REAL*8 or DOUBLE PRECISION variable causes the
following compiler warning message:

   warning FOR4165: underflow in REAL literal constant 2.225073858507201D-308

RESOLUTION
==========

Use the TINY() intrinsic function to convert a number to the smallest positive
REAL*8 value, and then use the result in your calculations.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this problem and will post new
information here in the Microsoft Knowledge Base as it becomes available.

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

Sample Code to Illustrate Problem and Workaround
------------------------------------------------

   C Compile options needed: none

         REAL*8 dx
         DOUBLE PRECISION dy
         dx = 2.225073858507201D-308  ! Warning - 0.000000000000000 assumed
         write (*,*) dx
         dy = tiny(1.d0)   ! work-around - dy = 2.225073858507201d-308
         write (*,*) dy
         END

Program Output
--------------

   0.000000000000000E+000
   2.225073858507201E-308

Additional query words: 4.00

======================================================================
Keywords          : kbFortranPS kbLangFortran kbbuglist
Technology        : kbAudDeveloper kbPTProdChange kbFortranSearch kbFORTRANPower400NT
Version           : :4.0

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

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