====================================================================== Microsoft(R) Product Support Services Application Note (Text File) WW1138: UPDATED CALCULATOR ACCESSORY FOR WINDOWS(TM) ====================================================================== Revision Date: 1/95 1 Disk The following information applies to Microsoft Windows and Windows for Workgroups, versions 3.10 and 3.11. --------------------------------------------------------------------- | 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 | | WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR | | 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. | | | | | | Copyright (C) 1995 Microsoft Corporation. All Rights Reserved. | | Microsoft and MS-DOS are registered trademarks and Windows is a | | trademark of Microsoft Corporation. Intel and Pentium are | | registered trademarks of Intel Corporation. | --------------------------------------------------------------------- Introduction ------------ 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. This rounding error is not related 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 ---------------------------- 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 NOTE: If you received this Application Note electronically, skip steps 3 and 4, and continue with step 5. 3. At the MS-DOS command prompt, type the following to create a new directory, then press ENTER md :\ where is your hard disk and is the name of the directory you want to create. For example, type: md c:\tempdir 4. Insert the enclosed WW1138 disk in the appropriate floppy disk drive, and copy WW1138.EXE from the WW1138 disk included with this Application Note to the newly created directory as follows copy :\ww1138.exe where is the floppy disk drive containing the WW1138 disk and is the drive and newly created directory. For example, if the directory is called TEMPDIR and is located on drive C and the WW1138 disk is in drive A, type the following command, then press ENTER: copy a:\ww1138.exe c:\tempdir 5. Change to the newly created directory (or, if you received this Application Note electronically, the directory to which you downloaded WW1138) by typing the following, then press ENTER cd\ where is the directory containing WW1138.EXE. 6. Type the following, then press ENTER: ww1138 7. Copy CALC.EXE to the Windows directory. For example, if Windows is installed in a directory on drive C called WINDOWS, type the following command, then press ENTER: copy 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 ---------------------------------------------------------------- 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.