Re: [ferret_users] if then masking inconsistency

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi-
IF returns  false for both missing-data and a value of zero. It looks 
like you have a valid value of zero here.  We introduced IFV in Ferret 
v6.71 to distinguish between the two cases, and avoid what you are 
seeing. That's described in the documentation, and here,
http://ferret.pmel.noaa.gov/Ferret/documentation/release-notes/version-6-7-1-release-notes

If you can't upgrade to a more recent version of Ferret you could design 
a mask that looks specifically for values of zero in your data field.

Ansley

On 5/5/2012 9:48 AM, Lev Tarasov wrote:
> Hi;
>   IF THEN masking seems to be breaking down in certain small
> regions of my field: my intermediate variable b7 doesn't retain
> the B6 value everywhere B6 is defined:
>
> yes? show var b7
>  B7 = IF B6 THEN B6 ELSE ((BEDTC-1)/2)^NTC
>
>
> yes? go digitize b6 nearest
>              VARIABLE : DGTEXPR[X=357.8092 ,Y=51.61662 ]
>              FILENAME : bedmBergscat255.nc
>              LONGITUDE: 2.2W
>              LATITUDE : 51.6N
>           0.0000000
> yes? go digitize b7 nearest
>              VARIABLE : DGTEXPR[X=357.8092 ,Y=51.61662 ]
>              FILENAME : bedmBergscat255.nc
>              LONGITUDE: 2.2W
>              LATITUDE : 51.6N
>         ....
>
>      NOAA/PMEL TMAP
>      FERRET v6.1
>      Linux(g77) 2.6.9-22. - 03/26/08
>       5-May-12 12:48
>
> What gives?
>
> cheers,
>
> lev
>
> Lev Tarasov -   Dept of Physics and Physical Oceanography,
>         Memorial University of Newfoundland.
>                 email: lev@xxxxxx
>                 http://www.physics.mun.ca/~lev/
>         Tel (709)-864-2675
>         Fax (709)-864-8739
>
>
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