he 'fill' algorithm puts back in a few data 
    points that would otherwise be missed by linear interpolation.
    __________________________________________________________________
 
    3D Interpolation
 
    Z=<a href="interplatlon.html">INTERPLATLON</a>(LATO,LONO,TO,ZO,LAT,LON,T) similarly performs a 3D
    interpolation, where TO is now time, with SIZE(ZO,3) being the same as
    LENGTH(TO).  LAT, LON, and T are all the same size.  
 
    Again, <a href="interplatlon.html">INTERPLATLON</a>(...,METHOD)