Re: how to define a 3-D variable

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

Hi Boyin,
Perhaps the best idea is for you to make your own version of the 
poly_vectors.jnl
script, and define a thinner arrow head.  You can find the script with 
the Unix
command "Fgo poly_vectors".   Copy it to your own journal script directory,
and rename it to for instance,  poly_vectors_thin.jnl  in which you 
change the
value of the arrowhead width.  Find the lines

  ! arrow head half-width (inches)
  let arrow_hd_half_wd = if (arrowhead_draw eq 0) then 0.05 else 0 
and change 0.05 to a smaller number, say 0.03.

The repeat command you tried does not work to fill a 3-D variable with
numbers; because of the way Ferret makes variable definitions. What you
have computed is the value for just the last iteration of the REPEAT.  You
could define a more complex mask to define the variable vv, or one can
draw the kind of plot you want with overlays:

 use coads_climatology
 set reg/l=1
 vec/color=blue (if sst lt 15 then uwnd),  (if sst lt 15 then vwnd)
 go fland
 vec/over/color=green (if sst lt 20 and sst gt 15 then uwnd),  (if sst 
lt 20 and sst gt 15 then vwnd)
 vec/over/color=purple (if sst lt 25 and sst gt 20 then uwnd),  (if sst 
lt 25 and sst gt 20 then vwnd)
 vec/over/color=red (if sst gt 25 then uwnd),  (if sst gt 25 then vwnd)

(Of course this can be cleaned up with a new title, and vector/nolabel 
commands).
This is not as satisfactory as using a version of poly_vectors.jnl, 
since the /COLOR=
option for the vector command has so few choices of colors.

Ansley

Boyin Huang wrote:

> Dear ferreters:
>
>
> The purpose is to control vector colors using vector
> routine (poly_vector routine is not good due to wide
> arrow head).
>
> Assume I have velocity V(x,y), I wish to separate it
> into a 3-D field VV(x,y,t) according to the 3rd
> variable (say SST). If I can do this, I will be able
> to plot series vector/over plot with different colors.
>
> Here is what I did:
>
> ----------------------------------------
> DEFINE AXIS/t=1:10:1/unit=none naxis
>
> repeat/range=1:10/name=m (let/t=`m` vv = if (sst gt
> `m`) then v)
>
> list vv[t=1]
> list vv[t=10]
> ----------------------------------------
> The listed values of vv[t=1] and vv[t=10] are same.
>
> I guess the problem is "let/t=..."
> Is there any way to define a new variable with
> additional dimension?
>
> Thanks
>
> =====
> Boyin Huang
> The Center for Research on the Changing Earth System (CRCES)
> 10211 Wincopin Circle, Suite 240
> Columbia, Maryland 21044
> Tel. 410-992-5300/19 (O), 410-461-9339(H) 
> Fax. 410-992-5944, Email. byh@crces.org 
> http://byh.crces.org
>
>
> 		
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