[ncl-talk] Interpolation error using linint1_n

[Giorgio Graffino]

Sorry Dennis, I messed up with the link and didn't check it before clicking "send"...
I checked my arrays with the function you suggested. It turns out that both are monotonic, one decreasing and the other increasing.
(0)    xi=1
(0)    xo=-1

Perhaps this is the problem: both xi and xo must be either increasing or decreasing. In a mixed case, the function fails. To confirm that, I ran the script with reversed xi (so both xi and xo are monotonically decreasing) and it went through with no problems.  

Thanks for your help,Giorgio


  ----Messaggio originale----
 
 Da: shea at ucar.edu
 
 Data: 5-giu-2019 18.41
 
 A: "Giorgio Graffino"<g.graffino at tim.it>
 
 Cc: "Ncl-talk"<ncl-talk at ucar.edu>
 
 Ogg: Re: [ncl-talk] Interpolation error using linint1_n
 

 

 
  
   [1] linint1_n is a 
   Built-In library function. It is not in the Contributed library as you indicated:
   

  
  
   http://www.ncl.ucar.edu/Document/Functions/Built-in/linint1_n.shtml
  
  
   

  
  
   [2] Both xi and xo must monotonic:
  
  
   

  
  
   h
   ttp://www.ncl.ucar.edu/Document/Functions/Contributed/isMonotonic.shtml
  
  
   

  
  
   print("xi="+
   isMonotonic(xi))
  
  
   print("xo="+
   sMonotonic(xo))
  
  
   

  
  
   

  
  
   

  
 
 

 
  
   On Wed, Jun 5, 2019 at 9:26 AM Giorgio Graffino <
   g.graffino at tim.it> wrote:
   

  
  
   
    Dear NCL people,
   
   
    I want to report a (potential) error in the documentation.
   
   
    

   
   
    While looking at how to interpolate a monotonically decreasing dimension from a 2D variable onto another, I found the linint1 functions (
    https://www.ncl.ucar.edu/Document/Functions/Contributed/linint1_n.shtml). It is said that the relevant dimension "must be strictly monotonically increasing or decreasing". However, when I run the function no output variable is created and the following warning appears
   
   
    

   
   
     warning:linint1_n: xi and xo must be monotonically increasing
   
   
    

   
   
    I'm using NCL 6.3.0 (quite old, I know) on a Linux cluster. Could it be the reason why a monotonically decreasing dimension is not accepted? Or is the documentation wrong?
    

   
   
    

   
   
    Cheers,
   
   
    Giorgio
    

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