 specifies the interpolation method,
    which defaults to 'linear'.
 
    Note that the 'fill' option does not work with 3D interpolation.
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    Usage: z=<a href="interplatlon.html">interplatlon</a>(lato,lono,[],zo,lat,lon);
           z=<a href="interplatlon.html">interplatlon</a>(lato,lono,[],zo,lat,lon,[],bool);
           z=<a href="interplatlon.html">interplatlon</a>(lato,lono,to,zo,lat,lon,t);
           z=<a href="interplatlon.ht