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Microsoft(R) Product Support Services Application Note (Text File)
WW1138: UPDATED CALCULATOR ACCESSORY FOR WINDOWS(R)
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Revision Date: 1/95 (B)
1 Disk Included
The following information applies to Microsoft Windows and Windows for
Workgroups, versions 3.10 and 3.11.
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| INFORMATION PROVIDED IN THIS DOCUMENT AND ANY SOFTWARE THAT MAY |
| ACCOMPANY THIS DOCUMENT (collectively referred to as an Application |
| Note) IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER |
| EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED |
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| PURPOSE. The user assumes the entire risk as to the accuracy and |
| the use of this Application Note. This Application Note may be |
| copied and distributed subject to the following conditions: 1) All |
| text must be copied without modification and all pages must be |
| included; 2) If software is included, all files on the disk(s) |
| must be copied without modification (the MS-DOS(R) utility |
| diskcopy is appropriate for this purpose); 3) All components of |
| this Application Note must be distributed together; and 4) This |
| Application Note may not be distributed for profit. |
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| |
| Copyright (C) 1995 Microsoft Corporation. All Rights Reserved. |
| Microsoft, MS-DOS, and Windows are registered trademarks of |
| Microsoft Corporation. Intel and Pentium are registered trademarks |
| of Intel Corporation. |
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Introduction
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The WW1138 disk included with this Application Note contains an
updated version of the Calculator accessory that is shipped with
Microsoft Windows 3.1x and Windows for Workgroups 3.1x. Previous
versions of Calculator display simple subtraction errors when you
subtract two numbers that include values to the right of the decimal
point. While Calculator is determining how to display the solution, it
encounters a loss of precision and shows an incorrect answer.
NOTE: This rounding error is unrelated to the floating-point unit
(FPU) in the Intel(R) Pentium(R) chip. This problem occurs only in
Calculator and does not affect Windows, other components in Windows,
or other Windows-based applications.
In addition to correcting the problem described above, the new
rounding algorithm in Calculator causes it to perform more like most
hand-held calculators. For example, if you enter the following
equation in the updated Calculator accessory or in a hand-held
calculator
[(1/3 + 10 - 10) x 3]
the result is 0.9999. The result in previous versions of Calculator is
1.0. The value 0.9999 is generated because significant digits are lost
by adding and subtracting 10. This is a secondary effect of the
changes made in Calculator to correct the precision errors.
To install the updated files
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1. Quit Windows, or open an MS-DOS command prompt within Windows.
2. Rename the existing CALC.EXE file in your Windows directory. For
example, if Windows is installed in a directory on drive C called
WINDOWS, type the following commands, pressing ENTER after each
line:
cd\windows
ren calc.exe calc.old
3. If you received a disk with this Application Note, insert the disk
in the appropriate floppy disk drive.
If you downloaded this Application Note from an online service,
skip to step 4. This procedure assumes that you have already
downloaded and extracted the compressed file.
4. At an MS-DOS command prompt, type the following and press ENTER
copy <source>:\calc.exe <location>
where <source> is either the letter of your floppy disk drive or
the directory containing the file you downloaded from online
services, and <location> is the path to your Windows directory. For
example, if you are installing from a floppy disk that you inserted
in drive A, and C:\WINDOWS is the path to your Windows directory,
type:
copy a:\calc.exe c:\windows
Or, for example, if you downloaded the WW1138.EXE file from online
services to C:\DOWNLOAD and C:WINDOWS is the path to your Windows
directory, type:
copy c:\download\calc.exe c:\windows
You are now ready to restart Windows (if necessary) and run the
updated Calculator accessory.
Steps to Reproduce Problem Using Previous Versions of Calculator
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1. To perform this test, choose two numbers that include values to the
right of the decimal point (for example, 12.52 and 12.51).
2. Double-click the Calculator icon in the Accessories group.
3. Enter the larger number first (for example, 12.52).
4. Press the MINUS SIGN (-).
5. Enter the smaller number (for example, 12.51).
6. Press the EQUAL SIGN (=).
Note that in this example you do not receive .01, the expected result.
Instead, you receive one of the following:
0.00
0.0099999999
0.010000001
The updated Calculator accessory displays the correct result, which is
.01.