ode45 help!!

I am trying to use the ode45 command, but I keep receiving error codes. I have changed so many things but I can not get it to work.

I want to plot the following:

• the position of the table and its velocity versus time for two or three periods.

• the velocity versus position.

Here is my current code along with the error messages:

function dx=project1(t,x)

m=20;

M=500;

k=50000;

l=2;

g=9.81;

wn=sqrt(4*k/(m+M));

T=(2*pi)/wn;

x0=-(m*g)/(4*k);

x0dot=-((m)/(m+M))*sqrt(2*g*l);

t=0:0.001:2*T;

xi=x0;

xidot=x0dot;

[t,x]=ode45(@project1, t, [xi xidot]);

figure;

plot(t,x(:,1));

xlabel('time');

ylabel('position');

figure;

plot(t,x(:,2));

xlabel('time');

ylabel('velocity');

function xdot=project1(~,x)

xdot1=x(2);

xdot2=-wn*wn*x(1);

xdot=[xdot1, xdot2];

end

end

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Error Message:

Error using odearguments (line 93)

PROJECT1/PROJECT1 must return a column vector.

Error in ode45 (line 115)

odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in project1 (line 23)

[t,x]=ode45(@project1, t, [xi xidot]);

Answer 1

[madhan ravi]

Just make the following changes in your code:

 function dx = project
 xdot = [xdot1; xdot2];