Subtracting the two resulting graghs of my ode program

I have two second order differential equations. I solved them with Ode45, but I want to subtract the two resulting answers from each other and plot the subtraction of the one answer from another one. How can I do that???

function dy=function1(t,y)
dy=zeros(2,1);
dy(1)=y(2);
dy(2)=sin(t)-y(1);
end

function dy=function2(t,y)
dy=zeros(2,1);
dy(1)=y(2);
dy(2)=(t^2)-2*y(1)-y(2);
end

[T,Y]=ode45(@function1,[0 10],[0 0]);
[M,X]=ode45(@function2,[0 10],[0 0]);
plot(T,Y(:,1),M,X(:,1))

I want to plot X(:,1)-Y(:,1)???

Answer 1

[Kelly Kearney]

You can either change the second input of both ode45 calls to specify specific time values to output:

tspan = linspace(0,10,100);
[T,Y]=ode45(@function1,tspan,[0 0]);
[M,X]=ode45(@function2,tspan,[0 0]);

(Here, T, M, and tspan will be equal).

Or, you could keep your original input but interpolate both output timeseries to the same grid:

y2 = interp1(T, Y, tspan);
x2 = interp1(M, X, tspan);
plot(tspan, y2(:,1)-x2(:,1));

[MA]

Thank you very much :)