potting the integral of a state

Hi everyone

I would like to enquire about integralting a state.Afer solving a state space equation on matlab sing ode45, how does one go about plotting the integral of a state, please kindly assist, thank you in advance!

Answer 1

[Torsten]

If y'(t)=f(t,y) is the state space equation, you get the integral of y by simultaneously solving z'(t)=y(t), z(0)=0.

[Basetsana Sebolao]

I see, I think I posed my question incorrectly. my apologies, My states (di) are respresented in a matrix, I have attached my code: By runnning the code below in the command window I am able to plot y(1), y(2), y(3), y(4) ( I have four states)

tspan = [0 0.005];

iniCon = [0; 0; 0; 0];

[t,y] = ode45(@sys, tspan, iniCon);

figure

cols = size(y,2);

for k = 1:cols

subplot(cols,1,k)

plot(t, y(:,k))

grid

xlim([0 1.5E-4])

title(sprintf('y_{%d}',k))

After plotting y(1), y(2), y(3), I am trying to plot the integrals of y(1), y(2) ...however, I am having a hard time plotting the integrals.

[Paul]

Implement what @Torsten suggested.

Change the last line of sys to:

di = [Ai + Bv; i];

Change iniCon to:

iniCon = [0;0;0;0;zeros(4,1)]; % assuming you want the integrals of y(i) to start from zero

Then y will have 8 states, the first 4 are i and the second 4 are the integrals of i