** Quiver plot. **

** QUIVER(X,Y,DX,DY) draws little arrows at every (X,Y) pair in **

** matrices X and Y. The (DX,DY) pairs in matrices DX and DY **

** determine the direction and magnitude of the arrows. **

** **

** **

** QUIVER(x,y,DX,DY), with two vector arguments replacing the first **

** two matrix arguments, must have length(x) = n and **

** length(y) = m where [m,n] = size(DX) = size(DY). In this case, the **

** arrows are the quads (x(j), y(i), DX(i,j), DY(i,j)). **

** Note that x corresponds to the columns of DX and DY and y corresponds **

** to the rows. **

** **

** **

** QUIVER(DX,DY) uses x = 1:n and y = 1:m. In this case DX and DY **

** are defined over a geometrically rectangular grid. **

** **

** **

** QUIVER(X,Y,DX,DY,S) and QUIVER(DX,DY,S) apply scalar S as a scale **

** factor to the lengths of the arrow. For example, S = 2 doubles **

** their relative length and S = 0.5 halves them. **

** **

** **

** A final trailing string argument specifies linetype and color using **

** any legal line specification as described under the plot command. **

** **

** **

** For example, try **

** xord = -2:.2:2; **

** yord = -2:.2:2; **

** [x,y] = meshgrid(xord,yord); **

** z = x .* exp(-x.^2 - y.^2); **

** [px,py] = gradient(z,.2,.2); **

** contour(x,y,z),hold on, quiver(x,y,px,py), hold off **

** **

** **

** See also GRADIENT , COMPASS , FEATHER , ROSE . **

** **