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#1
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Fouriertransformation
Hi,
Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Markus |
#2
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Fouriertransformation
Not usre why you want a FFT. I would format you trnad line (right click
trand line) and make it a polynomial of 6th order to get a more precise trandline. "maqqusz" wrote: Hi, Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Markus |
#3
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Fouriertransformation
"Joel" Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Not usre why you want a FFT. I would format you trnad line (right click trand line) and make it a polynomial of 6th order to get a more precise trandline. So I will explain it to you: The sunspots from the Sun have 11y long "cycles". With the FFT I want to detect them in the global temperature. So can anybody help me to do this with this Data in Excel? Markus |
#4
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Fouriertransformation
I think you are looking for an integral (not FFt) so you can get average
temperatures. The integral is the area under the curve. You can do a rectangular approximation to get the answer. For each time period create a rectangle with a triangle on top. the area of the rectangle is the time period times height of the first point. The area of the tirangle is (1/2 * time period) * absolute (2nd temperature - 1st temperature). Average temperature is total area calcualted above divided by the total time. "maqqusz" wrote: "Joel" Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Not usre why you want a FFT. I would format you trnad line (right click trand line) and make it a polynomial of 6th order to get a more precise trandline. So I will explain it to you: The sunspots from the Sun have 11y long "cycles". With the FFT I want to detect them in the global temperature. So can anybody help me to do this with this Data in Excel? Markus |
#5
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Fouriertransformation
Hallo,
I have asked how I can do a FFT with Excel. Markus "Joel" I think you are looking for an integral (not FFt) so you can get average temperatures. The integral is the area under the curve. You can do a rectangular approximation to get the answer. For each time period create a rectangle with a triangle on top. the area of the rectangle is the time period times height of the first point. The area of the tirangle is (1/2 * time period) * absolute (2nd temperature - 1st temperature). Average temperature is total area calcualted above divided by the total time. "maqqusz" wrote: "Joel" Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Not usre why you want a FFT. I would format you trnad line (right click trand line) and make it a polynomial of 6th order to get a more precise trandline. So I will explain it to you: The sunspots from the Sun have 11y long "cycles". With the FFT I want to detect them in the global temperature. So can anybody help me to do this with this Data in Excel? Markus |
#6
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Fouriertransformation
Can anybody tell me how I make a FFT-Transformation in Excel?
I have never used an AddIn before and so I don't know how to do ist. Hi. Not sure what version you have. Prior to Excel 2007, you first select Tools | AddIns, and select Data Analysis. Then, go back and select Tools | Data Analysis. The Fourier Program is about half way down the list. If you are getting an error, just note that the program does not work with blank data. Excel does not make the assumption that blank cells have a value of zero. You have to put a value in each of the 128 cells. If you are having a problem transforming the output into Sin/Cos Trig functions, note that there are different definitions of a fft. In Excel, note that the first output is the "Sum" of your data. Excel's equation is useful in Signal Processing, but not Data Analysis. An easy fix is to just divide the output by the size of your data. =IMDIV(B1,128) To find any dominate frequencies, a common technique is to take the Abs value of each complex number. =IMABS(B1) Plot these values using x-y scatter chart. Those frequencies that contribute the most will have a larger Abs value or "Peak". -- HTH :) Dana DeLouis Windows XP & Excel 2007 "maqqusz" wrote in message ... Hi, Can anybody tell me how I make a FFT-Transformation in Excel? I have never used an AddIn before and so I don't know how to do ist. My Values [2] I want to transform are yearly Temperatures from 1980 to 2006, so the Imaginary-value may be zeros. How do I do such a Transformation. There are 127 Values so if I add one unknown more it should be possible. [1] http://home.arcor.de/maqqusz/wetterr...temperatur.png [2] http://home.arcor.de/maqqusz/wetterr...Temperatur.xls [3] http://home.arcor.de/maqqusz/wetterr...Temperatur.txt Markus |
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