# Re: horizontal two-point correlations

From: Franco Catalano <franco.catalano_at_nyahnyahspammersnyahnyah>
Date: Thu, 24 Sep 2009 16:10:16 +0200

Hi Dennis,

I have a two-dimensional dataset z(y,x).
I need the one-dimensional autocorrelation function f(delta), where
f(0)=1 and delta is the increasing monotonic vector containing the
distancies between all (y,x) in the domain.
In your example, ra(y, delta_x) and rb(x, delta_y) are the
autocorrelation functions obtained considering, respectively x and y
directions alone, right?

Franco

Il giorno gio, 24/09/2009 alle 07.46 -0600, Dennis Shea ha scritto:
> Buongiorno
>
> Perhaps I am misunderstanding the question?
>
> z(t,x) where t and x are 'named' dimensions of size nt, nx
>
>
> mxlag = 3
> ra = esacr(z, mxlag) ; ===> ra(nt,mxlag)
> rb = esacr(z(x|:,t|:), mxlag) ; ===> rb(nx,mxlag)
>
> The latter uses NCL's dimension reordering
>
> http://www.ncl.ucar.edu/Document/Language/reorder.shtml
>
> More details are at:
> http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/index.shtml
> Click on "Variables"
> http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclVariables.shtml#NamedSubscripting
>
>
>
>
> Franco Catalano wrote:
> > Dear ncl developers and users,
> > Is there a ncl function to compute the autocorrelation coefficient for a
> > two-dimensional (x,y) dataset which considers separations delta at all
> > angles?
> > The function esacr considers only the rightmost dimension.
> > Thank you for any suggestions.
> >
> > Franco
> >

```--
____________________________________________________
Eng. Franco Catalano
Ph.D. Student
D.I.T.S.
Department of Hydraulics, Transportation and Roads.
Via Eudossiana 18, 00184 Rome
Sapienza University of Rome.
tel: +390644585218
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Received on Thu Sep 24 2009 - 08:10:16 MDT

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