what is the reason of an empty diagram?

I wrote a code in state space(I chose 10 state variables) and after using ode45 I want to plot xdot(10) that I defined it in function part.but when I run , it shows an empty diagram. can anybody help me solving this problem?

clc;clear;close all;

x0=[0;0;0;0;0;0;0;0;0;0];

t_sim=linspace(0,5,100);

k_ss=111177; %N/m

c_ss=3858.82; %N.m

k_s1=10000; %N/m

c_s1=1264.71; %N.m

k_s2=10117.7; %N/m

c_s2=1852.94; %N.m

r=0.49804; %m

l_1=1.011; %m

l_2=1.803; %m

m_1=40; %kg

m_2=35.5; %g

m_s=730; %kg

m_c=75; %kg

I_s=130; %kg.m^2

k_p1=175500; %N/m

k_p2=175500; %N/m

[t,x]=ode45(@func,t_sim,x0);

xdot=zeros(10,1);

xdot(10)=-(1/m_c)*(k_ss*(x(9)-x(5)+r*x(7))+c_ss*(x(10)-x(6)+r*x(8)));

plot(t,xdot(10));

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function xdot=func(t,x)

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Answer 1

[Star Strider]

It is likely necessary to index the variables appropriately.

Try this:

xdot10=-(1/m_c)*(k_ss*(x(:,9)-x(:,5)+r*x(:,7))+c_ss*(x(:,10)-x(:,6)+r*x(:,8)));

Then:

plot(t, xdot10) 

should work.

Since ‘func’ is not provided I cannot test this, so I am posting it as UNTESTED CODE.

[Tina M]

yes it works.tnx alot

[Star Strider]

As always, my pleasure!