fast fourier transform

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I was writing a code for fft where the user will input the number of samples. How do i loop all the butterfly diagrams so that it becomes an efficient program. what is the common factor between each stage of the butterfly diagram using which i can run a loop ???

Posted 5-Jun-12 18:06pm

9668762186

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nv3 · Answer 1 · 2012-06-05T21:38:00

Solution 1

There are tons of FFT algorithms around and the web is full of good descriptions of the theory and the algorithms. Why don't you start with a web search (google), develop some code, and come back here in case you run into problems.

Posted 5-Jun-12 21:38pm

nv3

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Member 11330011 29-Dec-14 5:50am

I like do fft for 1024 samples using c/c++ coding.What can i do?Please help me.

nv3 29-Dec-14 18:46pm

Just google "FFT algorithm C++" and you will find lots of code. If you want to understand what you are doing, perhaps start with
http://en.wikipedia.org/wiki/Fast_Fourier_transform
and keep on reading.

9668762186 · Answer 2 · 2012-06-06T01:22:00

i have written the code for the first stage butterfly which is :

C++

for (k=0;k<m;k++)
{
    while (l    {
        if (k%2==0)
        INT[k]=input[l]+W[0]*input[l+m/2];
        else
        INT[k]=input[l]+W[m/2]*input[l+m/2];
        l=l+1;
     }
}

but for the next stages there are too many variables like the input sample, the output sample,the twiddle factor.the problem i am facing is that i cant find a relation between them and hence cant understand how to run a loop so that the whole butterfly can be solved.

michaelmel · Answer 3 · 2012-06-06T15:01:00

Solution 3

Look up Cooley-Tukey algorithm on wiki, which has links to "simple, pedagogical" C and C++ implementations:

http://en.wikipedia.org/wiki/Cooley%E2%80%93Tukey_FFT_algorithm#Pseudocode[^]

Cooley-Tukey always was considered an FFT classic.

Posted 6-Jun-12 15:01pm

michaelmel

Updated 6-Jun-12 15:06pm

v3

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Member 11330011 29-Dec-14 6:18am

How the coding can be done in processor?please help me..