comp.dsp | Care to give me the IFFT of this 64 lines of data?

First column is line number, I need the IFFT if Second (b) and third column 
(c).

I used this function, but the result I got was different from another 
source.

--------------------------------------------
[a,b,c] = textread(...blah blah...);
f = b + i * c;

t = zeros(size(t1));
for j = 1:1:N
    t(j) = 1/N * sum( f' .* exp( i * 2 * pi * (0:1:(N-1)) * (j-1)/N) );
end
--------------------------------------------

Thanks.





-32 0.0  0.0
-31 0.0  0.0
-30 0.0  0.0
-29 0.0  0.0
-28 0.0  0.0
-27 0.0  0.0
-26 0.0  0.0
-25 0.0  0.0
-24 1.472 1.472
-23 0.0  0.0
-22 0.0  0.0
-21 0.0  0.0
-20 -1.472 -1.472
-19 0.0  0.0
-18 0.0  0.0
-17 0.0  0.0
-16 1.472 1.472
-15 0.0  0.0
-14 0.0  0.0
-13 0.0  0.0
-12 -1.472 -1.472
-11 0.0  0.0
-10 0.0  0.0
-9 0.0  0.0
-8 -1.472 -1.472
-7 0.0  0.0
-6 0.0  0.0
-5 0.0  0.0
-4 1.472 1.472
-3 0.0  0.0
-2 0.0  0.0
-1 0.0  0.0
0 0.0  0.0
1 0.0  0.0
2 0.0  0.0
3 0.0  0.0
4 -1.472 -1.472
5 0.0  0.0
6 0.0  0.0
7 0.0  0.0
8 -1.472 -1.472
9 0.0  0.0
10 0.0  0.0
11 0.0  0.0
12 1.472 1.472
13 0.0  0.0
14 0.0  0.0
15 0.0  0.0
16 1.472 1.472
17 0.0  0.0
18 0.0  0.0
19 0.0  0.0
20 1.472 1.472
21 0.0  0.0
22 0.0  0.0
23 0.0  0.0
24 1.472 1.472
25 0.0  0.0
26 0.0  0.0
27 0.0  0.0
28 0.0  0.0
29 0.0  0.0
30 0.0  0.0
31 0.0  0.0

I'll bite...

4.6E-002+4.6E-002i
0.132447302971407-2.33965523308187E-003i
-1.34730880654188E-002-7.85269119345812E-002i
-0.14275915814227+1.26515104039451E-002i
9.2E-002
-0.14275915814227+1.26515104039451E-002i
-1.34730880654188E-002-7.85269119345812E-002i
0.132447302971407-2.33965523308187E-003i
4.6E-002+4.6E-002i
-2.3396552330819E-003+0.132447302971407i
-7.85269119345812E-002-1.34730880654188E-002i
1.26515104039451E-002-0.14275915814227i
9.2E-002i
1.26515104039451E-002-0.14275915814227i
-7.85269119345812E-002-1.34730880654188E-002i
-2.33965523308191E-003+0.132447302971407i
4.6E-002+4.6E-002i
0.132447302971407-2.33965523308187E-003i
-1.34730880654188E-002-7.85269119345812E-002i
-0.14275915814227+1.26515104039451E-002i
9.2E-002
-0.14275915814227+1.26515104039451E-002i
-1.34730880654188E-002-7.85269119345812E-002i
0.132447302971407-2.33965523308187E-003i
4.6E-002+4.6E-002i
-2.3396552330819E-003+0.132447302971407i
-7.85269119345812E-002-1.34730880654188E-002i
1.26515104039451E-002-0.14275915814227i
9.2E-002i
1.26515104039451E-002-0.14275915814227i
-7.85269119345812E-002-1.34730880654188E-002i
-2.33965523308191E-003+0.132447302971407i
4.6E-002+4.6E-002i
0.132447302971407-2.33965523308187E-003i
-1.34730880654188E-002-7.85269119345812E-002i
-0.14275915814227+1.26515104039451E-002i
9.2E-002
-0.14275915814227+1.26515104039451E-002i
-1.34730880654188E-002-7.85269119345812E-002i
0.132447302971407-2.33965523308187E-003i
4.6E-002+4.6E-002i
-2.3396552330819E-003+0.132447302971407i
-7.85269119345812E-002-1.34730880654188E-002i
1.26515104039451E-002-0.14275915814227i
9.2E-002i
1.26515104039451E-002-0.14275915814227i
-7.85269119345812E-002-1.34730880654188E-002i
-2.33965523308191E-003+0.132447302971407i
4.6E-002+4.6E-002i
0.132447302971407-2.33965523308187E-003i
-1.34730880654188E-002-7.85269119345812E-002i
-0.14275915814227+1.26515104039451E-002i
9.2E-002
-0.14275915814227+1.26515104039451E-002i
-1.34730880654188E-002-7.85269119345812E-002i
0.132447302971407-2.33965523308187E-003i
4.6E-002+4.6E-002i
-2.3396552330819E-003+0.132447302971407i
-7.85269119345812E-002-1.34730880654188E-002i
1.26515104039451E-002-0.14275915814227i
9.2E-002i
1.26515104039451E-002-0.14275915814227i
-7.85269119345812E-002-1.34730880654188E-002i
-2.33965523308191E-003+0.132447302971407i

Confused Frank (Remove the dots) wrote:
> First column is line number, I need the IFFT if Second (b) and third column
> (c).
>
> I used this function, but the result I got was different from another
> source.
>
> --------------------------------------------
> [a,b,c] = textread(...blah blah...);
> f = b + i * c;
>
> t = zeros(size(t1));
> for j = 1:1:N
>     t(j) = 1/N * sum( f' .* exp( i * 2 * pi * (0:1:(N-1)) * (j-1)/N) );
> end
> --------------------------------------------
>
> Thanks.
>
>
>
>
>
> -32 0.0  0.0
> -31 0.0  0.0
> -30 0.0  0.0
> -29 0.0  0.0
> -28 0.0  0.0
> -27 0.0  0.0
> -26 0.0  0.0
> -25 0.0  0.0
> -24 1.472 1.472
> -23 0.0  0.0
> -22 0.0  0.0
> -21 0.0  0.0
> -20 -1.472 -1.472
> -19 0.0  0.0
> -18 0.0  0.0
> -17 0.0  0.0
> -16 1.472 1.472
> -15 0.0  0.0
> -14 0.0  0.0
> -13 0.0  0.0
> -12 -1.472 -1.472
> -11 0.0  0.0
> -10 0.0  0.0
> -9 0.0  0.0
> -8 -1.472 -1.472
> -7 0.0  0.0
> -6 0.0  0.0
> -5 0.0  0.0
> -4 1.472 1.472
> -3 0.0  0.0
> -2 0.0  0.0
> -1 0.0  0.0
> 0 0.0  0.0
> 1 0.0  0.0
> 2 0.0  0.0
> 3 0.0  0.0
> 4 -1.472 -1.472
> 5 0.0  0.0
> 6 0.0  0.0
> 7 0.0  0.0
> 8 -1.472 -1.472
> 9 0.0  0.0
> 10 0.0  0.0
> 11 0.0  0.0
> 12 1.472 1.472
> 13 0.0  0.0
> 14 0.0  0.0
> 15 0.0  0.0
> 16 1.472 1.472
> 17 0.0  0.0
> 18 0.0  0.0
> 19 0.0  0.0
> 20 1.472 1.472
> 21 0.0  0.0
> 22 0.0  0.0
> 23 0.0  0.0
> 24 1.472 1.472
> 25 0.0  0.0
> 26 0.0  0.0
> 27 0.0  0.0
> 28 0.0  0.0
> 29 0.0  0.0
> 30 0.0  0.0
> 31 0.0  0.0

This is a multi-part message in MIME format.

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Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Thank you BobM, your result tally with mine.=20

However, in the 802.11a specification, the result are like follows.=20
The format is one row with four pairs, numbered from with 0,1,2,3, etc.=20
The absolute values of both real and imaginary parts are fine, but pairs =
=20
with even number IDs have have opposite signs from our calculations.=20

What happened with the difference in signs?=20


## Re Im ## Re Im ## Re Im ## Re Im

0 0.046 0.046 1 -0.132 0.002 2 -0.013 -0.079 3 0.143 -0.013

4 0.092 0.000 5 0.143 -0.013 6 -0.013 -0.079 7 -0.132 0.002

8 0.046 0.046 9 0.002 -0.132 10 -0.079 -0.013 11 -0.013 0.143

12 0.000 0.092 13 -0.013 0.143 14 -0.079 -0.013 15 0.002 -0.132

16 0.046 0.046 17 -0.132 0.002 18 -0.013 -0.079 19 0.143 -0.013

20 0.092 0.000 21 0.143 -0.013 22 -0.013 -0.079 23 -0.132 0.002

24 0.046 0.046 25 0.002 -0.132 26 -0.079 -0.013 27 -0.013 0.143

28 0.000 0.092 29 -0.013 0.143 30 -0.079 -0.013 31 0.002 -0.132

32 0.046 0.046 33 -0.132 0.002 34 -0.013 -0.079 35 0.143 -0.013

36 0.092 0.000 37 0.143 -0.013 38 -0.013 -0.079 39 -0.132 0.002

40 0.046 0.046 41 0.002 -0.132 42 -0.079 -0.013 43 -0.013 0.143

44 0.000 0.092 45 -0.013 0.143 46 -0.079 -0.013 47 0.002 -0.132

48 0.046 0.046 49 -0.132 0.002 50 -0.013 -0.079 51 0.143 -0.013

52 0.092 0.000 53 0.143 -0.013 54 -0.013 -0.079 55 -0.132 0.002

56 0.046 0.046 57 0.002 -0.132 58 -0.079 -0.013 59 -0.013 0.143

60 0.000 0.092 61 -0.013 0.143 62 -0.079 -0.013 63 0.002 -0.132



"BobM" <BobM.DSP@gmail.com> wrote in message =
news:1125362472.819906.17650@z14g2000cwz.googlegroups.com...
> I'll bite...
>=20
> 4.6E-002+4.6E-002i
> 0.132447302971407-2.33965523308187E-003i
> -1.34730880654188E-002-7.85269119345812E-002i
> -0.14275915814227+1.26515104039451E-002i
> 9.2E-002
> -0.14275915814227+1.26515104039451E-002i
> -1.34730880654188E-002-7.85269119345812E-002i
> 0.132447302971407-2.33965523308187E-003i
> 4.6E-002+4.6E-002i
> -2.3396552330819E-003+0.132447302971407i
> -7.85269119345812E-002-1.34730880654188E-002i
> 1.26515104039451E-002-0.14275915814227i
> 9.2E-002i
> 1.26515104039451E-002-0.14275915814227i
> -7.85269119345812E-002-1.34730880654188E-002i
> -2.33965523308191E-003+0.132447302971407i
> 4.6E-002+4.6E-002i
> 0.132447302971407-2.33965523308187E-003i
> -1.34730880654188E-002-7.85269119345812E-002i
> -0.14275915814227+1.26515104039451E-002i
> 9.2E-002
> -0.14275915814227+1.26515104039451E-002i
> -1.34730880654188E-002-7.85269119345812E-002i
> 0.132447302971407-2.33965523308187E-003i
> 4.6E-002+4.6E-002i
> -2.3396552330819E-003+0.132447302971407i
> -7.85269119345812E-002-1.34730880654188E-002i
> 1.26515104039451E-002-0.14275915814227i
> 9.2E-002i
> 1.26515104039451E-002-0.14275915814227i
> -7.85269119345812E-002-1.34730880654188E-002i
> -2.33965523308191E-003+0.132447302971407i
> 4.6E-002+4.6E-002i
> 0.132447302971407-2.33965523308187E-003i
> -1.34730880654188E-002-7.85269119345812E-002i
> -0.14275915814227+1.26515104039451E-002i
> 9.2E-002
> -0.14275915814227+1.26515104039451E-002i
> -1.34730880654188E-002-7.85269119345812E-002i
> 0.132447302971407-2.33965523308187E-003i
> 4.6E-002+4.6E-002i
> -2.3396552330819E-003+0.132447302971407i
> -7.85269119345812E-002-1.34730880654188E-002i
> 1.26515104039451E-002-0.14275915814227i
> 9.2E-002i
> 1.26515104039451E-002-0.14275915814227i
> -7.85269119345812E-002-1.34730880654188E-002i
> -2.33965523308191E-003+0.132447302971407i
> 4.6E-002+4.6E-002i
> 0.132447302971407-2.33965523308187E-003i
> -1.34730880654188E-002-7.85269119345812E-002i
> -0.14275915814227+1.26515104039451E-002i
> 9.2E-002
> -0.14275915814227+1.26515104039451E-002i
> -1.34730880654188E-002-7.85269119345812E-002i
> 0.132447302971407-2.33965523308187E-003i
> 4.6E-002+4.6E-002i
> -2.3396552330819E-003+0.132447302971407i
> -7.85269119345812E-002-1.34730880654188E-002i
> 1.26515104039451E-002-0.14275915814227i
> 9.2E-002i
> 1.26515104039451E-002-0.14275915814227i
> -7.85269119345812E-002-1.34730880654188E-002i
> -2.33965523308191E-003+0.132447302971407i
>=20
> Confused Frank (Remove the dots) wrote:
> > First column is line number, I need the IFFT if Second (b) and third =
column
> > (c).
> >
> > I used this function, but the result I got was different from =
another
> > source.
> >
> > --------------------------------------------
> > [a,b,c] =3D textread(...blah blah...);
> > f =3D b + i * c;
> >
> > t =3D zeros(size(t1));
> > for j =3D 1:1:N
> >     t(j) =3D 1/N * sum( f' .* exp( i * 2 * pi * (0:1:(N-1)) * =
(j-1)/N) );
> > end
> > --------------------------------------------
> >
> > Thanks.
> >
> >
> >
> >
> >
> > -32 0.0  0.0
> > -31 0.0  0.0
> > -30 0.0  0.0
> > -29 0.0  0.0
> > -28 0.0  0.0
> > -27 0.0  0.0
> > -26 0.0  0.0
> > -25 0.0  0.0
> > -24 1.472 1.472
> > -23 0.0  0.0
> > -22 0.0  0.0
> > -21 0.0  0.0
> > -20 -1.472 -1.472
> > -19 0.0  0.0
> > -18 0.0  0.0
> > -17 0.0  0.0
> > -16 1.472 1.472
> > -15 0.0  0.0
> > -14 0.0  0.0
> > -13 0.0  0.0
> > -12 -1.472 -1.472
> > -11 0.0  0.0
> > -10 0.0  0.0
> > -9 0.0  0.0
> > -8 -1.472 -1.472
> > -7 0.0  0.0
> > -6 0.0  0.0
> > -5 0.0  0.0
> > -4 1.472 1.472
> > -3 0.0  0.0
> > -2 0.0  0.0
> > -1 0.0  0.0
> > 0 0.0  0.0
> > 1 0.0  0.0
> > 2 0.0  0.0
> > 3 0.0  0.0
> > 4 -1.472 -1.472
> > 5 0.0  0.0
> > 6 0.0  0.0
> > 7 0.0  0.0
> > 8 -1.472 -1.472
> > 9 0.0  0.0
> > 10 0.0  0.0
> > 11 0.0  0.0
> > 12 1.472 1.472
> > 13 0.0  0.0
> > 14 0.0  0.0
> > 15 0.0  0.0
> > 16 1.472 1.472
> > 17 0.0  0.0
> > 18 0.0  0.0
> > 19 0.0  0.0
> > 20 1.472 1.472
> > 21 0.0  0.0
> > 22 0.0  0.0
> > 23 0.0  0.0
> > 24 1.472 1.472
> > 25 0.0  0.0
> > 26 0.0  0.0
> > 27 0.0  0.0
> > 28 0.0  0.0
> > 29 0.0  0.0
> > 30 0.0  0.0
> > 31 0.0  0.0
> 
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	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
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<STYLE></STYLE>
</HEAD>
<BODY>
<DIV><FONT face=3DArial size=3D2>Thank you BobM, your result tally with =
mine.=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>However, in the 802.11a specification, =
the result=20
are like follows. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>The format is one row with four pairs, =
numbered=20
from with 0,1,2,3, etc. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>The absolute values of both real and =
imaginary=20
parts are fine, but&nbsp;pairs &nbsp;</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>with even number IDs have </FONT><FONT =
face=3DArial=20
size=3D2>have opposite signs from our calculations. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>What happened with the difference in =
signs?=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2><B><FONT=20
face=3DTimes-Bold size=3D1>
<P align=3Dleft>## Re Im ## Re Im ## Re Im ## Re Im</P></B></FONT><FONT=20
face=3DTimes-Roman size=3D1>
<P align=3Dleft>0 0.046 0.046 1 =960.132 0.002 2 =960.013 =960.079 3 =
0.143 =960.013</P>
<P align=3Dleft>4 0.092 0.000 5 0.143 =960.013 6 =960.013 =960.079 7 =
=960.132 0.002</P>
<P align=3Dleft>8 0.046 0.046 9 0.002 =960.132 10 =960.079 =960.013 11 =
=960.013 0.143</P>
<P align=3Dleft>12 0.000 0.092 13 =960.013 0.143 14 =960.079 =960.013 15 =
0.002=20
=960.132</P>
<P align=3Dleft>16 0.046 0.046 17 =960.132 0.002 18 =960.013 =960.079 19 =
0.143=20
=960.013</P>
<P align=3Dleft>20 0.092 0.000 21 0.143 =960.013 22 =960.013 =960.079 23 =
=960.132=20
0.002</P>
<P align=3Dleft>24 0.046 0.046 25 0.002 =960.132 26 =960.079 =960.013 27 =
=960.013=20
0.143</P>
<P align=3Dleft>28 0.000 0.092 29 =960.013 0.143 30 =960.079 =960.013 31 =
0.002=20
=960.132</P>
<P align=3Dleft>32 0.046 0.046 33 =960.132 0.002 34 =960.013 =960.079 35 =
0.143=20
=960.013</P>
<P align=3Dleft>36 0.092 0.000 37 0.143 =960.013 38 =960.013 =960.079 39 =
=960.132=20
0.002</P>
<P align=3Dleft>40 0.046 0.046 41 0.002 =960.132 42 =960.079 =960.013 43 =
=960.013=20
0.143</P>
<P align=3Dleft>44 0.000 0.092 45 =960.013 0.143 46 =960.079 =960.013 47 =
0.002=20
=960.132</P>
<P align=3Dleft>48 0.046 0.046 49 =960.132 0.002 50 =960.013 =960.079 51 =
0.143=20
=960.013</P>
<P align=3Dleft>52 0.092 0.000 53 0.143 =960.013 54 =960.013 =960.079 55 =
=960.132=20
0.002</P>
<P align=3Dleft>56 0.046 0.046 57 0.002 =960.132 58 =960.079 =960.013 59 =
=960.013=20
0.143</P>
<P align=3Dleft>60 0.000 0.092 61 =960.013 0.143 62 =960.079 =960.013 63 =
0.002=20
=960.132</P></FONT></FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>"BobM" &lt;</FONT><A=20
href=3D"mailto:BobM.DSP@gmail.com"><FONT face=3DArial=20
size=3D2>BobM.DSP@gmail.com</FONT></A><FONT face=3DArial size=3D2>&gt; =
wrote in=20
message </FONT><A=20
href=3D"news:1125362472.819906.17650@z14g2000cwz.googlegroups.com"><FONT =

face=3DArial=20
size=3D2>news:1125362472.819906.17650@z14g2000cwz.googlegroups.com</FONT>=
</A><FONT=20
face=3DArial size=3D2>...</FONT></DIV><FONT face=3DArial size=3D2>&gt; =
I'll=20
bite...<BR>&gt; <BR>&gt; 4.6E-002+4.6E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt; 9.2E-002<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
-2.3396552330819E-003+0.132447302971407i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt; 9.2E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
-2.33965523308191E-003+0.132447302971407i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt; 9.2E-002<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
-2.3396552330819E-003+0.132447302971407i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt; 9.2E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
-2.33965523308191E-003+0.132447302971407i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt; 9.2E-002<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
-2.3396552330819E-003+0.132447302971407i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt; 9.2E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
-2.33965523308191E-003+0.132447302971407i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt; 9.2E-002<BR>&gt;=20
-0.14275915814227+1.26515104039451E-002i<BR>&gt;=20
-1.34730880654188E-002-7.85269119345812E-002i<BR>&gt;=20
0.132447302971407-2.33965523308187E-003i<BR>&gt; =
4.6E-002+4.6E-002i<BR>&gt;=20
-2.3396552330819E-003+0.132447302971407i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt; 9.2E-002i<BR>&gt;=20
1.26515104039451E-002-0.14275915814227i<BR>&gt;=20
-7.85269119345812E-002-1.34730880654188E-002i<BR>&gt;=20
-2.33965523308191E-003+0.132447302971407i<BR>&gt; <BR>&gt; Confused =
Frank=20
(Remove the dots) wrote:<BR>&gt; &gt; First column is line number, I =
need the=20
IFFT if Second (b) and third column<BR>&gt; &gt; (c).<BR>&gt; =
&gt;<BR>&gt; &gt;=20
I used this function, but the result I got was different from =
another<BR>&gt;=20
&gt; source.<BR>&gt; &gt;<BR>&gt; &gt;=20
--------------------------------------------<BR>&gt; &gt; [a,b,c] =3D=20
textread(...blah blah...);<BR>&gt; &gt; f =3D b + i * c;<BR>&gt; =
&gt;<BR>&gt; &gt;=20
t =3D zeros(size(t1));<BR>&gt; &gt; for j =3D 1:1:N<BR>&gt;=20
&gt;&nbsp;&nbsp;&nbsp;&nbsp; t(j) =3D 1/N * sum( f' .* exp( i * 2 * pi * =

(0:1:(N-1)) * (j-1)/N) );<BR>&gt; &gt; end<BR>&gt; &gt;=20
--------------------------------------------<BR>&gt; &gt;<BR>&gt; &gt;=20
Thanks.<BR>&gt; &gt;<BR>&gt; &gt;<BR>&gt; &gt;<BR>&gt; &gt;<BR>&gt; =
&gt;<BR>&gt;=20
&gt; -32 0.0&nbsp; 0.0<BR>&gt; &gt; -31 0.0&nbsp; 0.0<BR>&gt; &gt; -30 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; -29 0.0&nbsp; 0.0<BR>&gt; &gt; -28 0.0&nbsp; =
0.0<BR>&gt; &gt;=20
-27 0.0&nbsp; 0.0<BR>&gt; &gt; -26 0.0&nbsp; 0.0<BR>&gt; &gt; -25 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; -24 1.472 1.472<BR>&gt; &gt; -23 0.0&nbsp; 0.0<BR>&gt; =
&gt; -22=20
0.0&nbsp; 0.0<BR>&gt; &gt; -21 0.0&nbsp; 0.0<BR>&gt; &gt; -20 -1.472=20
-1.472<BR>&gt; &gt; -19 0.0&nbsp; 0.0<BR>&gt; &gt; -18 0.0&nbsp; =
0.0<BR>&gt;=20
&gt; -17 0.0&nbsp; 0.0<BR>&gt; &gt; -16 1.472 1.472<BR>&gt; &gt; -15 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; -14 0.0&nbsp; 0.0<BR>&gt; &gt; -13 0.0&nbsp; =
0.0<BR>&gt; &gt;=20
-12 -1.472 -1.472<BR>&gt; &gt; -11 0.0&nbsp; 0.0<BR>&gt; &gt; -10 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; -9 0.0&nbsp; 0.0<BR>&gt; &gt; -8 -1.472 -1.472<BR>&gt; =
&gt; -7=20
0.0&nbsp; 0.0<BR>&gt; &gt; -6 0.0&nbsp; 0.0<BR>&gt; &gt; -5 0.0&nbsp;=20
0.0<BR>&gt; &gt; -4 1.472 1.472<BR>&gt; &gt; -3 0.0&nbsp; 0.0<BR>&gt; =
&gt; -2=20
0.0&nbsp; 0.0<BR>&gt; &gt; -1 0.0&nbsp; 0.0<BR>&gt; &gt; 0 0.0&nbsp; =
0.0<BR>&gt;=20
&gt; 1 0.0&nbsp; 0.0<BR>&gt; &gt; 2 0.0&nbsp; 0.0<BR>&gt; &gt; 3 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; 4 -1.472 -1.472<BR>&gt; &gt; 5 0.0&nbsp; 0.0<BR>&gt; =
&gt; 6=20
0.0&nbsp; 0.0<BR>&gt; &gt; 7 0.0&nbsp; 0.0<BR>&gt; &gt; 8 -1.472 =
-1.472<BR>&gt;=20
&gt; 9 0.0&nbsp; 0.0<BR>&gt; &gt; 10 0.0&nbsp; 0.0<BR>&gt; &gt; 11 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; 12 1.472 1.472<BR>&gt; &gt; 13 0.0&nbsp; 0.0<BR>&gt; =
&gt; 14=20
0.0&nbsp; 0.0<BR>&gt; &gt; 15 0.0&nbsp; 0.0<BR>&gt; &gt; 16 1.472 =
1.472<BR>&gt;=20
&gt; 17 0.0&nbsp; 0.0<BR>&gt; &gt; 18 0.0&nbsp; 0.0<BR>&gt; &gt; 19 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; 20 1.472 1.472<BR>&gt; &gt; 21 0.0&nbsp; 0.0<BR>&gt; =
&gt; 22=20
0.0&nbsp; 0.0<BR>&gt; &gt; 23 0.0&nbsp; 0.0<BR>&gt; &gt; 24 1.472 =
1.472<BR>&gt;=20
&gt; 25 0.0&nbsp; 0.0<BR>&gt; &gt; 26 0.0&nbsp; 0.0<BR>&gt; &gt; 27 =
0.0&nbsp;=20
0.0<BR>&gt; &gt; 28 0.0&nbsp; 0.0<BR>&gt; &gt; 29 0.0&nbsp; 0.0<BR>&gt; =
&gt; 30=20
0.0&nbsp; 0.0<BR>&gt; &gt; 31 0.0&nbsp; 0.0<BR>&gt; =
</FONT></BODY></HTML>

------=_NextPart_000_0015_01C5AD4D.7D0E66B0--

> Frank wrote:
> 
> Thank you BobM, your result tally with mine.
> 
> However, in the 802.11a specification, the result are like follows.
> The format is one row with four pairs, numbered from with 0,1,2,3, etc.
> The absolute values of both real and imaginary parts are fine, but pairs
> with even number IDs have have opposite signs from our calculations.
> 
> What happened with the difference in signs?

It might arise from slightly different definitions of
the FFT. Some people use exp (-jw) and some use exp(jw).

Erik

-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"Neither noise nor information is predictable."
  -- Ray Kurzweil

"Erik de Castro Lopo" <nospam@mega-nerd.com> wrote in message
news:4313D34D.334D869A@mega-nerd.com...
> > Frank wrote:
> >
> > Thank you BobM, your result tally with mine.
> >
> > However, in the 802.11a specification, the result are like follows.
> > The format is one row with four pairs, numbered from with 0,1,2,3, etc.
> > The absolute values of both real and imaginary parts are fine, but pairs
> > with even number IDs have have opposite signs from our calculations.
> >
> > What happened with the difference in signs?
>
> It might arise from slightly different definitions of
> the FFT. Some people use exp (-jw) and some use exp(jw).
>
> Erik
>
> -- 

The specifications says IFFT for transmitter, so I expect it to be jw and
divide
the final sequence by 1/N. Anyway, I will keep this difference in mind and
get
my coding started.

Care to give me the IFFT of this 64 lines of data?

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