(arrowx, arrowy, npts, fill);
Set the style for the arrow used by
plvect to plot vectors.
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.
Number of points in the arrays
fill is true then the
arrow is closed, if
is false then the arrow is open.
plsvect(arrowx, arrowy, fill)
This function is used in example 22.