Nearest defined neighbor function

[Patrick Reuter]

Dear all,

I have a variable which is only defined over the sea, elsewhere there
are undefined values. Is there a function in Grads that can draw me a
map where at locations of undefined values, instead of leaving it
blank, draws me the value of the nearest defined value of the
8-neighborhood ? I tried smth9, but it does not exactly what I want.

Can anybody help?

Thanks in advance

  Patrick