Set the style for the arrow used by plvect to plot vectors.
arrowx, arrowy
(PLFLT *,input)
Pointers to a pair of arrays containing the x and y points
which make up the arrow. The arrow is plotted by joining these
points to form a polygon. The scaling assumes that the x and y
points in the arrow lie in the range
-0.5 <= x,y <= 0.5.
npts
(PLINT,input)
Number of points in the arrays
arrowx and
arrowy.
fill
(PLINT,input)
If fill = 0 then the
arrow is open, if fill = 1
then the arrow is filled.