FIX: You may receive results that are not correct when you perform mathematical computations that involve floating point arithmetic in Visual C++ .NET 2003

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Article ID: 834421 - View products that this article applies to.
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When you perform mathematical computations that involve floating point arithmetic in Microsoft Visual C++ .NET 2003, you may receive results that are not correct.


A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Visual Studio .NET 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Date         Time   Version   		Size        File name
01-Aug-2004  14:04  13.10.4008.0  	86,046      Cl.exe
01-Aug-2004  14:04  13.10.4008.0     1,867,776      C2.dll


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


Steps to reproduce the problem

  1. Create a Console Application project in Visual C++ 2003.
  2. Make the following code changes:
    #include <stdio.h>
    #include <math.h>

    void sub( int arg )
    double a = 1.0 - sqrt(225.0) / 36.0;
    double b = 1.0 + (arg-30.0) /70.0;

    if( b > 2.0 ) b = 2.0;

    double c = b * a * 9.0;

    printf( "%f\n",c);
    // Release = 14.378571 (NG)
    // Debug = 5.325000 (OK)


    void main( void )

  3. Build the application by using a Release configuration.
  4. Run the application.
The expected result is 5.325000, but the result that you receive is 14.378571.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates


Article ID: 834421 - Last Review: October 25, 2005 - Revision: 1.3
  • Microsoft Visual C++ .NET 2003 Standard Edition
  • Microsoft Visual C++ .NET 2002 Standard Edition
  • Microsoft Visual C++, 32-bit Enterprise Edition 6.0 SP5
kbbug kbfix kbqfe kbprb kbhotfixserver KB834421

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