load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

 ntim = 10
 nlat = 4
 mlon = 6

 x    = random_normal(0,10,(/ntim,nlat,mlon/))
 x!0  = "time" 
 x!1  = "lat" 
 x!2  = "lon" 
 
 cf   = ezfftf(x)
 printVarSummary(cf)                ; (2,ntim,nlat,mlon/2)

 cf(:,:,:,1:)  = 0.0
 x1   = ezfftb (cf, 0.0)   
 copy_VarMeta(x, x1)
 print(x1)

 x2   = x1(lat|:,lon|:,time|:)

 nxy  = nlat*mlon
 X2   = onedtond(ndtooned(x2), (/nxy, ntim/) ) 
 printVarSummary(X2)

 if(any(ismissing(X2))) then
    print("X2 contains one or more missing values, cannot continue!!.")
    return
  end if

 xxx = dimsizes(X2)
 nx  = xxx(0)
 nt  = xxx(1)
 print("nx="+nx+"   nt="+nt)

 do i=0,nx-1
  pmin = min(X2(i,:))
  pmax = max(X2(i,:))
  if(pmin.eq.pmax) then
    print("X2 contains all constant values at nx = " + i)
  end if
end do