% Starting diary file diary-22-Nov-2010.txt

edit ode23tx
help ode23
help odeset

help meshgrid
[y1,y2] = meshgrid(-15:.5:15);
whos
y1
y2
altitude = y1.^2 + (y2/1000).^2;
altitude
whos
surf(altitude)

edit valleyf.m
ode23(@valleyf, [0 10],  [0;10])

[T,Y] = ode23(@valleyf,[0 10], [0;10]);
size(T)
size(Y)
nsteps = length(T)
close all; surf(y1,y2,altitude); hold on; plot(Y(:,1),Y(:,2),'r.');

[T,Y] = ode23(@valleyf,[0 10], [.1;10]);
nsteps = length(T)
close all; surf(y1,y2,altitude); hold on; plot(Y(:,1),Y(:,2),'r.');

[T,Y] = ode23s(@valleyf,[0 10], [.1;10]);
nsteps = length(T)
close all; surf(y1,y2,altitude); hold on; plot(Y(:,1),Y(:,2),'r.');

diary off