[ncl-talk] ind funtion (not working when used as: ind(variable.eq.variable at _FillValue)

[Mary Haley]

Rashed,

For assorted reasons, you do NOT want to directly compare an array with its
_Fillvalue.

Please see this description in the NCL Reference Manual on the "if"
statement and read the discussion about _FillValue:

http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclStatements.shtml#If

You should also read the section on "Expressions and missing values" at:

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

The use of "ismissing" to check for missing values is the correct way to go.

--Mary



On Sun, Nov 19, 2017 at 11:05 PM, Rashed Mahmood <rashidcomsis at gmail.com>
wrote:

> Hi,
> NCL 6.4:
> I am not sure if that is the intended behaviour, a simple following
> command show the problem:
> I do not why the command line: ncl 2> print(ind(a.eq.a at _FillValue)) would
> produce a missing while it's fine with: ncl 3> print(ind(ismissing(a)))
>
>
> ncl 0> a = (/1,2,3,4,-999.000,6/)
> ncl 1> a at _FillValue = -999.000
> ncl 2> print(ind(a.eq.a at _FillValue))
> (0)     -2147483647 <(214)%20748-3647>
> ncl 3> print(ind(ismissing(a)))
> (0)     4
>
>
> If that is how it is supposed to, then should there be any warning/error
> message?
>
> Thanks,
> Rashed
>
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