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How do I solve the following second order differential equation?

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John O'Brian
John O'Brian am 22 Okt. 2017
Kommentiert: John O'Brian am 26 Okt. 2017
Can you give me the code on how to solve the following equation?
1.4x'' + 4x' + 1700x = - [-8x' + 20(x')^3 + 100x - 2.5x^3]
Thanks!

Antworten (1)

Ramanuja Jagannathan
Ramanuja Jagannathan am 25 Okt. 2017
Please find below the documentation link showing how to represent differential equations in MATLAB and solve them. https://www.mathworks.com/help/symbolic/solve-a-single-differential-equation.html
Hope this helps
  2 Kommentare
John O'Brian
John O'Brian am 25 Okt. 2017
Bearbeitet: Torsten am 26 Okt. 2017
Hi I have the following code:
syms y(t)
[V] = odeToVectorField(1.4*diff(y, 2) == 8*diff(y)-20*(diff(y)).^3-100*y+2.5*y.^3-4*diff(y)-1700*y);
M = matlabFunction(V,'vars', {'t','Y'});
sol = ode45(M,[0 20],[0.01 0]);
opts = odeset('OutputFcn',@odephas2); % Options Structure
tspan = linspace(0, 1, 100); % Times For Evaluation
ic = [0 1]; % Initial Conditions
[t, xt] = ode45(EqnFcn, tspan, ic);
figure(1)
[t, xt] = ode45(EqnFcn, tspan, ic, opts);
title('Phase Plane Plot')
axis equal
figure(2)
plot(t, xt)
grid on
title('Time Domain Plot')
EqnSubc = regexp(sprintf('%s\n',Eqn_subs), '\n','split');
legend(EqnSubc{1:end-1})
I am trying to plot a phase plane plot for a variety of initial conditions. I think it might require a for loop. Can you adjust the code and show me how to do it please?
John O'Brian
John O'Brian am 26 Okt. 2017
actually can you help me with this attached file? thanks!

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