% Matlab diary from cs111, Nov 26 2007.
%
% This is what I typed in class.  
%
% Type it into Matlab yourself to
% reproduce the output I showed.

diary on
swinger
clc
timespan = [ 0 10 ]
help ode23tx
ode23tx('f', timespan, 1);
xlabel('time t')
ylabel('function values y(t)')
exp(10/2)
exp(5/2)
hold on
plot([1:10], exp([1:10]/2),'r')
clc
clf
close all

% now edit f to end with ydot = -y/2;
ode23tx('f', timespan, 1);
% now edit f to end with ydot = t/2;
ode23tx('f', timespan, 1);

clc
edit lotka
ode23tx('lotka',[0 20],[300;150]);
legend('rabbits','foxes')
ode23tx('lotka',[0 20],[15 ; 22])
ode23tx('lotka',[0 20],[102 ; 198])
ode23tx('lotka',[0 20],[100 ; 200])
axis([0 20 0 300])
clc
ode23tx('lotka',[0 20],[300;150]);
[T,Y] = ode23tx('lotka',[0 20],[300;150]);
T
Y
plot(T, Y(:,1))
plot(T, Y)
plot(Y(:,1), Y(:,2))
xlabel('rabbits')
ylabel('foxes')
title('Phase Space Plot')

diary off