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Fast Fourier Transform help..
Can anyone offer us a suggestion on where to find information about FFT in
Excel? The VBA Analysis Toolpak offers a function called ATPVBAEN.XLA!Fourier . We'd like to know more about it's parameters and abilities. We want to convert a time domain force vector into REAL force versus frequency for the binary data segment. |
#2
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Fast Fourier Transform help..
We'd like to know more about <Fourier parameters and abilities.
Do you have any specific questions? It's a Radix-2 Algorithm only. Arbitrarily limited to 2^12, or 4096 data points. It's a Subroutine, and can only be called with data on a worksheet. (Too bad...best to have your own fft program in vba). VBA editor "debug.print" statements in previous 2 versions caused this to run extremely slow. Fixed in 2007. Can work with either "i" or "j" complex strings (ie 2+3i or 2+3j). The frequency domain includes all the data (good for signal processing, etc) but to do data analysis etc you need to divide by the size of the data. [for example, use IMDIV( ) ]. Another annoyance for the spreadsheet interface is that blank cells are not treated as zero. FFt will trigger an error with blank cells. The algorithm itself is really good though. -- Dana DeLouis Windows XP & Excel 2007 "mark" wrote in message ... Can anyone offer us a suggestion on where to find information about FFT in Excel? The VBA Analysis Toolpak offers a function called ATPVBAEN.XLA!Fourier . We'd like to know more about it's parameters and abilities. We want to convert a time domain force vector into REAL force versus frequency for the binary data segment. |
#3
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Fast Fourier Transform help..
Hello, Dana,
I'm the one that posted, but not the one that wanted to use it, so I don't know the specific question. Thanks for your post. I will pass it along to the person who wanted it on Monday. How I got involved is that the company Help Desk has me listed as the local Excel expert. Thanks, Mark |
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