[ferret_users] convert z axis form negative to positive: following older solution, meeting a new problem with defining axis

[Tingting Wang <Tingting.Wang@xxxxxx>]

Dear ferret users
  I am trying to convert the z axis of the model output to another: 
from originally increasing in negative to inversed axis (increasing in 
positive). I found the same problem in Users' Mail Archive, and tried to 
solve it following David's suggestion.
  
http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2009/msg00582.html

> yes? save/clobber/prec=7/file=ztmp.asc abs(z[gz=s])
> yes? sp tac ztmp.asc > z.asc
>
> Now in a new Ferret session,
> yes? file/var=zz z.asc
> yes? define axis/z/depth zax = zz[d=z.asc]
> yes? use/order=xy-z state.0000000000.glob.nc 
> <http://state.0000000000.glob.nc/>
> yes? let snew = s[gz=zax@asn]
  But when I defined a new axis, there are always errors!

> yes? define axis/z/depth zax = zz[d=z.asc]
> **TMAP ERR: Inappropriate ioctl for device
>                            Last or next-to-last record read Zbnds
>          history FERRET V6.61 7-Jun-10
>                      Date set: ./z.asc
>                      Date file:./z/asc
> yes? define axis/z/depth zax = zz[d=z.asc]
> **TMAP ERR: Success
>                            during SKIP reads
>                           Date set: ./z.asc
>                           Date file:./z/asc
> yes? show axis zax
>    name                   axis              #pta                   
> start                      end
   Definitely, there is something wrong. Unfortunately, I can't see the 
mistake.
   Thank you very much in advance!

Yours sincerely,
Tingting