Microsoft KB Archive/94934

= Microsoft Knowledge Base =

Excel: Fourier Analysis Tool Returns Error Message
Last reviewed: September 12, 1996

Article ID: Q94934

The information in this article applies to:

- Microsoft Excel for Windows, versions 4.0 and 4.0a - Microsoft Excel for the Macintosh, version 4.0

SUMMARY
When you use the Fourier Analysis tool included with Microsoft Excel version 4.0, an error message may be displayed and analysis may halt if your data is not in the correct number format.

The second sentence of the second paragraph on page 52 of the &quot;Microsoft Excel User's Guide 2&quot; states

Complex data must be in either the x+yi or x+yj format. However, the x+yj format is only acceptable for version 4.0 of Microsoft Excel for the Macintosh -- you cannot use this format with version 4.0 of Microsoft Excel for Windows.

Also on page 52, the last sentence of the second paragraph states that

If x is a negative number, it must be preceded by an apostrophe ('), or  Microsoft Excel will display an error message. This statement is only partially true: a negative number needs to be preceded by an apostrophe only if it contains an imaginary component. Negative numbers that do not have an imaginary component do not need to be preceded by an apostrophe or any other character.

MORE INFORMATION
You can use the Fourier Analysis tool to solve problems in linear systems and to analyze periodic data. It is one of two Engineering Analysis tools included with the Microsoft Excel 4.0 Analysis ToolPak.

With the Fourier Analysis tool, you can select both an input and an output range for data and you also have the option to perform a reverse Fourier transform. Data entered into the input range must conform to the following formatting conventions:

 Numbers that have both real and imaginary components or a complex number (such as 1+2i, 3-5i, -7i) must be entered as text. In Microsoft Excel for Windows, the imaginary component must contain the letter &quot;i&quot;. In Microsoft Excel for the Macintosh, the imaginary component must contain either the letter &quot;i&quot; or the letter &quot;j&quot;, but not both. For example, &quot;1+2i&quot; is acceptable on both the Windows and Macintosh versions of Microsoft Excel, but &quot;3-4j&quot; would only be acceptable on the Macintosh.  Numbers that do not have an imaginary component (2, 7, -5, 3.14159, etc.) must be entered as numbers; these numbers cannot be entered as text strings. For example, &quot;2&quot; or '2 would not be a valid entry, but 2 would be a valid entry. If you enter a number that does not contain an imaginary component as text, and later include it in the input range, the Fourier Analysis tool will return one the following error messages: Microsoft Excel for Windows ---      An error has occurred locating a support file or processing data for an add-in procedure. Microsoft Excel for the Macintosh -      Fourier Analysis: Input range contains invalid data. 