[ncl-talk] Interpolation error using linint1_n

Giorgio Graffino g.graffino at tim.it
Fri Jun 7 10:15:31 MDT 2019

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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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