r = mod([1:1000]-1,5)+1
sort\up r
generate t 0,1.8,,200
t[201:400] = t[1:200]
t[401:800] = t[1:400]
t[801:1000] = t[1:200]
z = exp(-r/2)*cosd(180*(r-1))
grid\xyout\size\-messages 10 r*cosd(t) r*sind(t) z m x y
!
nx = 10 ! number of subdivisions in x
ny =  5 ! number of subdivisions in y
ww = bivsmooth(x,y,m,nx,ny)
!
nrows = vlen(ww)[1]
ncols = vlen(ww)[2]
!
u = ww[1,2:ncols]
v = ww[2:nrows,1]
w = ww[2:nrows,2:ncols]
!
set colormap rainbow
clear
window 5
density x y m
window 7
density u v w