Re: array addition

  Hi Agnes,

  Some functions

  http://www.ncl.ucar.edu/Document/Functions/Contributed/dim_sum_Wrap.shtml
  http://www.ncl.ucar.edu/Document/Functions/Built-in/dim_sum.shtml

  will do that. The above could be used for (say) total precipitation
  at each grid point

    prcTot = dim_sum_Wrap( prc(lat|:, lon|:, time|:) )

  For (say) 4x-daily [6hr totals] to get daily totals: prc(time,lat,lon)

    nDay = ntim/4
    prcDay = new ((/nDay,nlat,mlon/),typeof(prc),getFillValue(prc))

    ndy = -1
    do nt=0,ntim-1,4
       ndy = ndy+1
       prc(ndy,:,:) = dim_sum( prc(lat|:, lon|:, time|nt:nt+3) )
    end do

  -----
  The following will do it for all dimensions.
  http://www.ncl.ucar.edu/Document/Functions/Built-in/sum.shtml
  -----
  However, if you are talking about element by element sum

    D = A + B + C

  where A@_FillValue, A@_FillValue, C@_FillValue
  then you would have to trick NCL. EG:

    A@_FillValue = 0.0 ; change to zero
    B@_FillValue = 0.0
    C@_FillValue = 0.0

    delete(A@_FillValue)
    delete(B@_FillValue)
    delete(C@_FillValue)

    D = A + B + C

  D

  Agnes Lim Huei Ni wrote:
> Hi Dennis,
  I may not be too clear in my previous post.
> Though there is a missing value, I still want it to sum and return
> the remaining sum instead of a missing value if one of the three
> elements is missing.
> Is that possible?

> Agnes

> Dennis Shea wrote:
  NCL automatically does that. See:

 
http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclExpressions.shtml#MissingValues

  Agnes Lim Huei Ni wrote:
> Hi
  I have three arrays that I wish to sum. However, the elements of
> missing values are different in each of them.
> How should i code the script in order for the array to sum only
> valid values.
> Or does NCL already automatically does that.
  Agnes
> _______________________________________________
> ncl-talk mailing list
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Mon May 04 2009 - 07:51:58 MDT