clf
set(0,'defaulttextinterpreter','latex')
 
F1=@(x,y) exp(x).*cos(y); F2=@(x,y) -exp(x).*sin(y);
x=linspace(0,4,20);y=linspace(-2,2,21);
[X,Y]=meshgrid(x,y);
quiver(X,Y,F1(X,Y),F2(X,Y),1.5,'LineWidth',1.2)
hold on
axis([.5,5.5,-2.5,2.5])
axis equal
%set(gca,'YTickLabel',{})
% set(gca,'XTickLabel',{}) 
% set(gca,'ZTickLabel',{})
 text(-.5,2.2,'$\mathbf{F}(x,y) = e^x\cos y \mathbf{i} -e^x\sin y\mathbf{j}$','FontSize',14)

pause
 [X,Y]=meshgrid(0:0.1:4,-2:.1:2);
 falt=@(x,y) exp(x).*sin(y);
Z=falt(X,Y);
contour(X,Y,Z,[-24:3:-1 1:3:24],'k')
 te=text(-.5,-2.3,'F\"altlinjer: $e^x\sin y =C$','FontSize',14);
pause
 pot=@(x,y) exp(x).*cos(y);
 contour(X,Y,pot(X,Y),10,'r')
 delete(te)
 text(-.5,-2.3,'Ekvipotentialkurvor: $e^x\cos y =C$','FontSize',14,'Color','r');
axis equal