RE: [ferret_users] set a single point to be zero

[Jaison Kurian <jaison@xxxxxxxxxxxxxxxxxx>]

Hi Jaci,
         Well, specifying i and j alone works fine for me (with
Ferret versions 5.53, 5.80 and 6.00).

     use levitus_climatology
     let temp0 = IF I EQ 40 AND J EQ 100 THEN 0 ELSE temp
     list/k=1/i=40/j=100 temp, temp0
                 DATA SET: /home/DATA/fer_dsets/data/levitus_climatology.cdf
                 LONGITUDE: 59.5E
                 LATITUDE: 9.5N
                 DEPTH (m): 0
      Column  1: TEMP is TEMPERATURE (DEG C)
      Column  2: TEMP0 is IF I EQ 40 AND J EQ 100 THEN 0 ELSE TEMP
                 TEMP   TEMP0
      I / *:     27.60  0.0000

However, you can also set the default grid for a session by using
"SET GRID" command. You can set the grid using either a variable
name

       set grid variablename[d=1]

or by using exact grid name from a ferret session

       use levitus_climatology
       show grid temp
       set grid GMS1

Please have a look at section 'Ref Sec31.5.  SET GRID' of user manual
for more details. User manual recommends this command to "Specify the 
default grid for abstract expressions".

Hope this helps,

Regards,

Jaison



On Thu, 15 Mar 2007, Jaclyn Brown wrote:

> Thanks for all the advice on this problem.
> 
> The solution is:
> 
> let uvel_blank = if (i[gx=uvel] eq 59 and j[gy=uvel] eq 93) then 0 else  
> uvel
> 
> Note that
> 
> let uvel_blank = if i eq 59 and j eq 93 then 0 else uvel
> will not work as ferret doesn't know what i and j are.
> 
> Cheers,
> Jaci
> 
> ----------------------------------------------------------------------------
> On 14Mar 2007, at 12:22 PM, Jaclyn Brown wrote:
> 
> > Hi
> >
> > I have a 4-D data file in x,y,z, t and I'd like to change one x-y  
> > point to zero to make it a land point.
> >
> > ie. uvel(i=59,j=93)=0
> >
> >
> >
> > I can't find a ferret command that will let me do this.
> >
> > Any ideas?
> >
> > Thanks,
> >
> > Jaci
> >
> >
> >
> > Dr Jaclyn Brown
> >
> > Postdoctoral Associate
> >
> > Dept Geology and Geophysics
> >
> > Yale University
> >
> >
> >
> > Ph. 203 432 1959
> >
> >
> >
> > PO Box 208109
> >
> > New Haven CT 06520
> >
> > USA
> >
> >
> >
> >
> 
>