% Matlab diary from cs110a, Mar 7 2005.
%
% This is what I typed in class.  
%
% Type it into Matlab yourself to
% reproduce the output I showed.

f = @(t,y) -[2*y(1) ; y(2)/500] / norm([2*y(1) ; y(2)/500])
% The next line should have 0.01 instead of 0.1 , corrected later in class
ode23(f, [0 10], [0.1 ; 10])  
legend('y(1)= East', 'y(2) = West')
legend('y(1)= East', 'y(2) = North')
tspan = [0 10];
y0 = [0.1 ; 10]  % should be 0.01 again
[T,Y]=ode23(f,tspan,y0);steps=length(T),plot(Y(:,1),Y(:,2),'.');axis equal; shg
plot(Y(:,2))
plot(Y(:,1))
plot(Y(:,1),'.')
ode23(f, [0 10], [0.01 ; 10])
y0 = [0.01 ; 10]
[T,Y]=ode23(f,tspan,y0);steps=length(T),plot(Y(:,1),Y(:,2),'.');axis equal; shg
plot(Y(:,1),'.')
plot(Y(:,1))
ode23s(f, [0 10], [0.01 ; 10])
[T,Y]=ode23s(f,tspan,y0);steps=length(T),plot(Y(:,1),Y(:,2),'.');axis equal; shg
plot(Y(:,1))