Re: [ferret_users] if then masking inconsistency

[Russ Fiedler <russell.fiedler@xxxxxxxx>]

Hi Lev,

Zero values evaluate to FALSE in Ferret.

>From the documentation

http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/commands-reference/IF

>From V6.71 there is a new way of masking which allows zeros to be
evaluated as true IFV

http://ferret.pmel.noaa.gov/Ferret/documentation/release-notes/users-guide/variables-xpressions/XPRESSIONS#_VPID_181

If you need to use your old version I suppose

let  B7 = IF ( B6 OR B6 EQ 0 ) THEN B6 ELSE ((BEDTC-1)/2)^NTC

or

let  B7 = IF ( B6 NE `B,RETURN=bad` ) THEN B6 ELSE ((BEDTC-1)/2)^NTC


Will work.

Russ



On Sun, 2012-05-06 at 02:48 +1000, 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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