From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>

Date: Thu Aug 22 2013 - 09:39:11 MDT

Date: Thu Aug 22 2013 - 09:39:11 MDT

Actually, I had the population and sample variances mixed up.

It should be

svar = variance(Test1) ; sample variance

pvar = svar*(N-1.)/N ; population variance of Test1

print("")

print("pvar="+pvar+" svar="+svar)

; scale to population variance

total_area = (px(0) + px(N/2-1))*(df/2) + sum(px(1:N/2-2))*df

sclVar = pvar/total_area

pxscl = px*sclVar

On 8/22/13 9:22 AM, Dennis Shea wrote:

*> Not sure what is meant by:
*

*> "But I want this pick to be over the value 4, not 50. The 4, in this
*

*> case, means the frequency with which the 2 repeats"
*

*>
*

*> ---
*

*> specx_anal scales the spectra such that the area under
*

*> the curve equals the variance of the input series.
*

*> This facilitates determining the variance at a particular
*

*> frequency interval or at a frequency
*

*>
*

*> fstrt = 0.20
*

*> flast = 0.30
*

*> ifrq = ind(frq.ge.fstrt .and. frw.le.flast)
*

*> varf = sum(px*df)
*

*>
*

*> At an individual frequency fstrt=flast (must be exact)
*

*>
*

*>
*

*>
*

*> Attached is a simple script you can use. It uses ezfftf to explicitly
*

*> calculate the fourier coefficients and then the periodogram.
*

*>
*

*> Note: I think your script had
*

*>
*

*> do i = 1, dimsizes(listTest21) -1
*

*>
*

*> Should be
*

*> do i = 1, dimsizes(listTest21)
*

*>
*

*> but maybe I am wrong.
*

*>
*

*>
*

*> On 8/22/13 8:17 AM, Rodrigo Colpo wrote:
*

*>> Dear all,
*

*>>
*

*>>
*

*>> I have created a list where the number "2" is equally spaced, like this:
*

*>>
*

*>>
*

*>> [0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0,
*

*>> 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0,
*

*>> 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0,
*

*>> 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2,
*

*>> 0, 0, 0, 2, 0, 0, 0]
*

*>>
*

*>> ... using the following script:
*

*>>
*

*>>
*

*>> Test1 = new(100,integer)
*

*>> Test1 = 0
*

*>> do i = 1, dimsizes(listTest21) -1
*

*>> if (i%4 .eq. 0) then
*

*>> Test1(i-1 ) = 2
*

*>> end if
*

*>> end do
*

*>>
*

*>> So, every 4 elements, there is one "2".
*

*>>
*

*>> Then, I used the "specx_anal" function the have information about the
*

*>> "frequency", and ploted the following graph of the periodogram (@spcx):
*

*>> https://docs.google.com/file/d/0BxhksDtMuWrVdTVIdkdJcWVUVVE/edit?usp
*

*>>
*

*>> But I want this pick to be over the value 4, not 50. The 4, in this
*

*>> case, means the frequency with which the 2 repeats (or have
*

*>> oscillations in the "numbers").
*

*>>
*

*>> The idea is to apply this principle to retrieve information about the
*

*>> time scale needed for clouds to change its "behavior".
*

*>>
*

*>> Best wishes,
*

*>> Rodrigo.
*

*>>
*

*>>
*

*>>
*

*>> _______________________________________________
*

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*

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*

*>>
*

*>
*

*>
*

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Received on Thu Aug 22 09:39:16 2013

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