# [ncl-talk] regression with lag

Sancta Vega sanctavega at gmail.com
Tue Oct 3 02:58:28 MDT 2017

```Hi Kevin thank you for your suggestion.
I don't want value of n to increase by 2 every loop iteration but normally
from 0 to 20 in order to get 21 as "nlagr".

I removed the "n=-1" and "n=n+1" but still getting same error as before.
do n=0,nlagr-1
Regdata(:,:,n) =regline(x(0:Nend-n-yLag), P1(:,:,yLag+n:Nend))
end do ;

2017-10-03 1:44 GMT+02:00 Kevin Hallock <hallock at ucar.edu>:

> Hi,
>
> I noticed in your code’s do-loop that you’re incrementing n independently
> of the loop.
>
> If you modify the loop to include “print(n)”:
> do n=0,nlagr-1
>       n = n+1
>       print(n)
>       Regdata(:,:,n) =regline(x(0:Nend-n-yLag), P1(:,:,yLag+n:Nend))
> end do ;
>
> you can see that the only values of “n” used in the “Regdata(:,:,n) =…”
> line are (/1,3,5,7,9,11,13,15,17,19,21/), because n is being incremented
> by both the loop structure itself and the “n = n+1” line.
>
> If this is intentional and you want your value of n to increase by 2 every
> loop iteration, you could cleanly write this by adding a third
> comma-separated value on the “do n=“ line, for example:
> do n=0,nlagr-1,2
>       print(n)
> end do
>
> Otherwise, you might want to try removing the “n = n+1” line and rerunning
>
> Regarding the subscript error you experienced, I believe that the final 21
> value mentioned above is causing the error you’re seeing, as the third
> dimension of Regdata is “nlagr” elements long — 21 in this case, with valid
> indices ranging from 0 to 20, inclusive.
>
> I hope this helps,
> Kevin
>
> On Oct 2, 2017, at 8:25 AM, Sancta Vega <sanctavega at gmail.com> wrote:
>
> according to this answer  https://www.ncl.ucar.edu/Suppo
> rt/talk_archives/2013/2968.html
>
> I need the 10 positive and negative lag regression  of my data x(time),
> P1(lat,lon,time) but I dont loop trough lat lon .
>
> This is my code :
>
> dim_s   = dimsizes(P1)  ;;;
>  Nend = 5000 ; length of  x
>  nlagr= 21 ; +- 10 lag
>   yLag = 10
>
>  Regdata              = new((/dim_s(0),dim_s(1),nlagr/),"float")
>
> n=-1
> do n=0,nlagr-1
>       n= n+1
>        Regdata(:,:,n) =regline(x(0:Nend-n-yLag), P1(:,:,yLag+n:Nend))
> end do ;
>
>
> This give me an error :
> fatal:Subscript out of range, error in subscript #2
> fatal:An error occurred reading P1
>
> I try to replace regline by regCoef and get the same error message.
>
>
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