FEATHER(Z) draws a graph that displays the angle and magnitude
of the complex elements of Z as arrows emanating from equally
spaced points along a horizontal axis.
FEATHER(X,Y) is equivalent to FEATHER(X+i*Y). It displays the
feather plot for the angles and magnitudes of the elements of
matrices X and Y.
FEATHER(Z,'S') and FEATHER(X,Y,'S') use line style 'S' where
'S' is any legal linetype as described under the PLOT command.
See also COMPASS , ROSE , QUIVER .