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Re: [ferret_users] Reg: period calculation in FFT


Here is the documentation for FFTA,


It says
...   the units of the returned time axis are "cycles/Dt" where Dt is the time unit of the input axis. 

So you still use 1./a where a is a variable containing the time coordinates of your time axis, and the units will be cycles/hour. 


On 7/18/2018 9:13 PM, milik a wrote:
Dear ferreters,

Please help me and thanks in advance.

I have a query regarding defining period  in FFT. The example below is for monthly navy winds in ferret.
! Define the period from the frequency axis. (From FFT demo)
      LET per = 1./a

Here 1./a for monthly data (If I am correct). If I have hourly data, what should the the value in place of 1.

And also if it is weekly and 15 days data what should be taken. I have both hourly data and 15 days data. I am confused in taking this value. 

Please help.
Thank you.

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