the time can reach more than 90 seconds (in my case).

Hi. Yes, I have terrible times also. I don't know why.

Just for a comparison:
On my vista machine, my custom vba FFT program that works at full precision (28 digits) takes 0.2 seconds for size 4096.
Therefore, a standard double precision routine should be much faster.
(Also, a custom FFT program will not have an arbitrary limit of 2^12)

--
Dana DeLouis


"Dimitry" wrote in message ...

Thanks Dana!

It was a helpful hint. But the 2007 remains slower. The problem is that
there are live formulas in any open Workbook. The cell formating leads to
additional delay. You can see this in the next example. If you open more
Workbooks with formulas the time can reach more than 90 seconds (in my case).

Sub Demo()
Const FFT As String = "ATPVBAEN.XLAM!Fourier"

'// Set up - CHANGING VALUES in col.A
' FFT over col B

Range("A1:A4096").Formula = "=Rand()"
Range("A1:A4096").Select
Selection.Copy
Range("B1:B4096").Select
Selection.PasteSpecial xlPasteValues
Application.CutCopyMode = False
' "Rand()" in A1:A4096 are still alive
'time for calc is not in the test intervals

For I = 1 To 4

'// Timing Test 1
Tme1 = Timer 'Start time 1

Run FFT, [B1:B4096], Cells(1, (I + 6)), False, False
Cells((I), 3) = I
Cells((I), 4) = (Timer - Tme1)
Next I
Cells((I), 3) = "[A]=Rand()"
Cells((I), 4) = " Time_1,s"
Cells((I + 1), 3) = "FFT ([b]= CONST)"
Range("K1:K4096").Value = " "

'// Set up - CONSTANTS in col.A
' FFT over col B

Range("A1:A4096").Select
Selection.Copy
Selection.PasteSpecial xlPasteValues
Application.CutCopyMode = False
' <A1:A4096 are constants

For J = 1 To 4

'// Timing Test 2
Tme2 = Timer 'Start time 2

Run FFT, [B1:B4096], Cells(1, (J + 11)), False, False
Cells((J), 5) = J
Cells((J), 6) = (Timer - Tme2)

Next J
Cells((J), 5) = "[A]=Const"
Cells((J), 6) = " Time_2,s"
Cells((J + 1), 5) = "FFT ([b]= CONST)"
End Sub


Thanks again,
Dimitry


"Dana DeLouis" wrote:


Excel 2003. The only differences is in Analysis ToolPaks -



ATPVBAEN.XLAM!Fourier in Excel 2007 and ATPVBAEN.XLA!Fourier in Excel

2003. I

Hi. Actually, 2003 should be much slower because Microsoft left in
Debug.Print statements in the Analysis ToolPak that caused the programs to
run very, very, slow.
They refused to fix this for some unknown reason. Having said that, my
times in Excel 2007 are around 4.3 seconds vs your 12 seconds. (for size
4096)
You are right, this is still very slow! I don't have a reason for it
being so slow.
You may want to consider your own vba Fourier Program. The advantages
are that you can keep the Real & Imaginary values in two separate arrays.
When Calling FFT, you do not have to waste time joining each into a
string, and them placing them on a worksheet. It is much faster this way.

I get 4.3 seconds with Windows Vista and Excel 2007.

Sub Demo()
Const FFT As String = "ATPVBAEN.XLAM!Fourier"
Const Forward As Boolean = False
Const Inverse As Boolean = True
Const NoLabels As Boolean = False
Const HasLabels As Boolean = True

Dim Tme As Double
Dim Rng As Range

'// Set up
[A:C].Clear
Set Rng = [A1].Resize(2 ^ 12)

With Rng
.Formula = "=Rand()"
.Copy
.PasteSpecial xlPasteValues
Application.CutCopyMode = False
End With

'// Timing Test
Tme = Timer 'Start time
Run FFT, Rng, [C1], Forward, NoLabels
MsgBox Timer - Tme
End Sub


--
HTH :)
Dana DeLouis


"Dimitry" wrote in message
...

Fast Fourier Transform (FFT) in Excel 2007 is 10 to 30 times slower than

in

Excel 2003. The only differences is in Analysis ToolPaks -
ATPVBAEN.XLAM!Fourier in Excel 2007 and ATPVBAEN.XLA!Fourier in Excel

2003. I

have a doubt about compression in *.xlam format. It seems like these

files

are unwrapped every time when a macro calls them. I have to calculate

more

than 12800 FFTs in one workbook. Each one takes 12 seconds. The macro

with

FFT should work more than two days. Any suggestions how to accelerate

FFT in

Excel 2007?
Thanks