Plotting third order differential equation using ode45
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Hello
Could you please how to plot below third order differential equation using ODE45.
d3x/dt3 = +-1
采纳的回答
Ameer Hamza
2020-12-6
编辑：Ameer Hamza
2020-12-6
You need to convert this 3-rd order ODE to 3 first order ODEs. Also due to +-1, you have two systems of ODEs. Try following code
odeFun = @(t,x,a) [x(2);
x(3);
a];
tspan = [0 10];
IC = [1; 0; 0];
ode45(@(t,x) odeFun(t,x,1), tspan, IC)
hold on
ode45(@(t,x) odeFun(t,x,-1), tspan, IC)
legend({'$x$', '$\dot{x}$', '$\ddot{x}$'}, 'Interpreter', 'latex', 'FontSize', 16, ...
'Location', 'best')
2 个评论
vaibhav gupta
2020-12-6
编辑：vaibhav gupta
2020-12-6
Ameer Hamza
2020-12-7
Try this
odeFun = @(t,x,a) [x(2);
x(3);
a];
tspan = [0 10];
IC = [1; 0; 0];
[t, y] = ode45(@(t,x) odeFun(t,x,1), tspan, IC);
plot(t, y(:,1))
hold on
[t, y] = ode45(@(t,x) odeFun(t,x,-1), tspan, IC);
plot(t, y(:,1))
legend({'$+1$', '$-1$'}, ...
'Interpreter', 'latex', ...
'FontSize', 16, ...
'Location', 'best')
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