Re: [ferret_users] Variable Unknown Problem

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

Hi John,
When you are doing a block IF statement, do not use the continuation 
character \ .  These are all separate commands but your use of the 
continuation character concatenates them all into a single command. 
You've given Ferret the single long command quoted in the error message. 
I haven't checked all your commands in detail but your script should 
work if you remove all the backslashes.

There is another syntax in Ferret for checking the value of script 
arguments. It's a very compact syntax, but once you learn it, it's more 
direct. (Look up "go scripts, writing GO tools in the Users Guide 
index.) It lets you check a single value of a symbol or several allowed 
values for argument 3. You can check for them as follows

IF  ($theVar1%0|XX>1|>0%) THEN
  IF ($3%0|temp>1|salt>1|u>1|v>1|*>0%) THEN
     cancel region/z
     let sig = z[gz=$3]
     let depthValues = sig * ( depth + zeta )
...

The first line says, If symbol ($theVar1) has no value, substitute 0, or 
if it has the value XX then substitute 1, and if it has no value at all, 
substitute 0. Evaluate the symbol, using the syntax ($symbolname).  So 
the argument of the IF is 1 only if ($theVar1) is XX.

The second line says, if ($3) has no value substitute 0.  If it is temp, 
salt, u, or v, substitute 1, and if it is anything else substitute 0.  
So the argument to the second IF is true only if ($3) is temp, salt, u, 
or v.

John Schattel wrote:

> Hi All,
>
> I am trying to execute some code (see at bottom) to regrid data that 
> is on a sigma vertical axis onto a grid that is on a depth coordinate 
> and am getting the error:
>
> * **ERROR: variable unknown or not in data set: 
> DEPTHVALUES[X=@MIN,Y=@MIN,Z=@MIN,T=@MIN] cancel region/z let sig = 
> z[gz=u] let depthValues = sig * ( depth + zeta ) LET zmin = 
> `depthValues[x=@min,y=@min,z=@min,t=@min]` LET zmax = 
> `depthValues[x=@max,y=@max,z=@max,t=@max]` define 
> axis/z=`zmin`:`zmax`:10/units=meters/depth zdepth let var1OnDepth = 
> zaxreplace(u,depthValues,z[gz=zdepth]) let var1IsOnZ = "true" Command 
> file, command group, or REPEAT execution aborted *.
>
> Any suggestions why Ferret doesn't recognize DEPTHVALUES?
>
> Regards,
>
> John
>
> IF `strcmp("($theVar1)", "XX") ne 0.0`  THEN \
>    (if `strcmp("($3)","temp") eq 0.0 or strcmp("($3)","salt") eq 0.0 
> or strcmp("($3)","u") eq 0.0 or strcmp("($3)","v") eq 0.0` then \
>       cancel region/z \
>       let sig = z[gz=$3] \
>       let depthValues = sig * ( depth + zeta ) \
>       LET zmin = `depthValues[x=@min,y=@min,z=@min,t=@min]` \
>       LET zmax = `depthValues[x=@max,y=@max,z=@max,t=@max]` \
>       define axis/z=`zmin`:`zmax`:10/units=meters/depth zdepth \
>       let var1OnDepth = zaxreplace($3,depthValues,z[gz=zdepth]) \
>       let var1IsOnZ = "true" \
>    else \
>       let var1IsOnZ = "false" \
>    endif) \
> endif