Can not get vector field

Hello,

I try to plot vector field given by the formula:

in order to do so I defined:

y = 0:0.1:100;

x = -y;

and finaly try to plot it by quiver(x,y)

Unfortunately instead of vector filed around unit circle I get

Also, I feel like I don't get this from math perspective as well. The author says that this formula should give circular vector field which should be intuitively visibile - how, I don't see it right away.

Thanks for the clarification.

Answer 1

[KSSV]

y = 0:0.1:100;
x = -y; 
[X,Y] = meshgrid(x,y) ;
quiver(X,Y)

[Marcin R]

Thanks for the answer but this does not seem correct. Here is the plot I am looking for:

[KSSV]

r = 1 ;  % Radius of circle 
C = [0 0 ] ;    % Origin of circle 
th = linspace(0,2*pi,100) ; % 

x = C(1) + r*cos(th) ;
y = C(2) + r*sin(th) ;

plot(x,y,'b')
hold on
idx = 1:10:100 ;  
quiver(x(idx),y(idx),-y(idx),x(idx))

[Marcin R]

Thanks, this is exactly what I was looking for.