MATLAB: How to plot phase plane in MATLAB

phase planeplot

Hi I have two equations here, and I wonder that how do you plot them as a phase plane.
du/dt = wu^2 – Bu dw/dt = A – w – wu^2
and A,B both are constants

Best Answer

Alex, assuming that you are talking about a u-w (position-velocity, sort of) phase plot, here you go. Essentially, you only need to solve the differential equations and then plot the result.
function my_phase()
[~,X] = ode45(@EOM,[0 50],[1 1]);
u = X(:,1);
w = X(:,2);
plot(u,w)
xlabel('u')
ylabel('w')
grid
end
function dX = EOM(t, y)
dX = zeros(2,1);
u  = y(1);
w  = y(2);
A  = 1;
B  = 1;
dX = [w*u^2 - B*u;...
      A - w - w*u^2];
end
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