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Fourier Analysis Excel 2007 array size error

Posted on 2011-03-10
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This is Excel 2007.  I did a Fourier Analysis over an array of 512 real numbers yielding an array of 512 complex numbers.
Then I tried to do a 2nd array of the same size.
The function errors out saying that the arrays need to be sized a power of 2.  512 is a power of two.
The exact row numbers are x3:x514.
514 -3 +1 is 512 rows of course......
Please help!
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Question by:Fred Marshall
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by:SiddharthRout
ID: 35104566
512 is a valid size as it is a power of two. Can I see the code that you are using?

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by:SiddharthRout
ID: 35104803
Also I want to see how are you populating the 2nd array? You might want to try this to check if it is actually a 512 sized array?

'~~> Replace MyArray with the name of the array
Debug.Print Ubound(MyArray)

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by:Fred Marshall
ID: 35104963
I didn't do anything re: arrays really.

I just used the Fourier Analysis Input Range and Output Range pretty much like I said originally.

$E$3:$E$514
$H$3:$H$514

Just for the heck of it I did this:
I ran it over 256 cells and got the results.
Then I repeated those cells to get 256
Then I did an Inverse over the 512 and it worked fine.

The Inverse values are purely real as expected.
But, when I try to format them down to 1 or 2 decimal places they don't change at all!

I don't know how to do the Debug.Print Unbound thing......
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by:SiddharthRout
ID: 35104972
I used the same range and didn't get an error?

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by:SiddharthRout
ID: 35104975
BTW when I say Error I am referring to your main array size error.

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SiddharthRout earned 500 total points
ID: 35105235
>>>The Inverse values are purely real as expected.
But, when I try to format them down to 1 or 2 decimal places they don't change at all!

I see what you mean...

That is because the numbers are stored as text. See snapshot 1. If you convert them to number then you will get the desired results. (See snapshot 2)

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Untitled.jpg
Untitled2.jpg
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by:Fred Marshall
ID: 35105948
Now it says that all the complex numbers have to have the same suffix either "i" or "j" but they were generated by Excel!!

I don't get the error you show to work on...
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by:SiddharthRout
ID: 35105960
Can you upload your file?

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by:Fred Marshall
ID: 35106019
I did find an error.  One of the input arrays had some blank cells in it.  Seems to be working better now.
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by:SiddharthRout
ID: 35106120
Gr8 :)

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Author Closing Comment

by:Fred Marshall
ID: 35108587
I likely would not have noticed this little pastel icon/button nor known what to do with it.  It helped quite a bit in fixing this problem!
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