How to put fft for xy graph???

[darksea]

I have one 2D array and I want to do 1D FFT for every row of that 2D array. I am now using for loop to auto index every row and do FFT. Obviously, the loop is time consuming because the array is big. Is there any VI or method to do FFT parallelly for every row?

Thanks...

[Milqman]

I don't think there is a way to do it faster.  The number of computations it takes to calculate the FFT is constant for each subarray.  Doing them in some other order is not going to help (I think).  To test it, you could just index every subarray out into a 1xn and have an FFT for each one.  Time them, and see how it goes.  I have a feeling you are doing it the best way.

Best,
~milq

[darksea]

Milqman, thanks for your reply.....  I am considering to use c code. I hope it will be faster.

[altenbach]

If you have a multi processor machine or a multicore processor, you might be able to keep both CPUs busy by e.g. processing two rows in parallel. How big are the rows?

Just try some simple code variations and do some benchmarks. No guarantees. 🙂

[darksea]

1000 rows.... And I don't have duo core processor.... 

[Milqman]

shhh . . . don't tell anybody I said this . . .

/whisper
matlab might be a better option
//whisper

You CAN keep a secret right?

😉
~milq

[darksea]

%whisper

Actually, I totally agree with you..... I would like to use matlab or c...

%whisper

[johnsasikennedy@gmil.com]

i need it urgent. pls tell me how to do it.. i need fft for 50 hz frequency

[altenbach]

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johnsasikennedy@gmil.com wrote:

i need it urgent. pls tell me how to do it.. i need fft for 50 hz frequency

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(First of all, you don't have a 2D fft, so appending to this old thread is offtopic.)

Well, if you know "dt", you can calculate "df" to be applied to the waveform graph. No xy graph needed.

Besides, your question is too terse to really give an answer. Why don't you add some diagram comments to your VI explaining whats wrong with it.

Your X data is NOT equally spaced, so you also need to either resample at a fixed dt or use the unevenly sampled tool. Resampling is probably simpler.

[johnsasikennedy@gmil.com]

I am new to labview.

Will u pls help me out and send me the program for the 2 txt document...????

I need it urgent.