oppgave381

%a
x = 0:pi/10:2*pi;
y = x;
[x,y] = meshgrid(x,y);
u = cos(x);
v = sin(x);
quiver(x,y,u,v);
%b
x = -2:.5:2;
y = x;
[x,y] = meshgrid(x,y);
v = -x./(x.^2+y.^2).^(3/2);
u = -y./(x.^2+y.^2).^(3/2);
quiver(x,y,u,v)
%c
x = -1:0;
y = x;
[x,y] = meshgrid(x,y);
u = ((1-x)/((x-1).^2+y.^2))+ ((1+x)/((x+1).^2+y.^2))
v = ((-y)/((x-1).^2+y.^2))+ ((y)/((x+1).^2+y.^2))
quiver(x,y,u