Why do I get undefined variable error in the attached code?

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What's wrong with my code? I can't figure it out, I'm a beginner. Please help.

See screenshots attached. I'm trying to plot and show that the system is non linear.

The error says "undefined Cw1"

[KALYAN ACHARJYA]

here Cw1 and Cw2 are not in input data within the function, then how you assigned x(1)=Cw1.. ..so on, So either you have to consider Cw1, Cw2 as input during function call or it should be defined before assigned as x(1)=Cw1.

[OCDER]

Did you mean to say this?

Cw1 = x(1);  
Cw2 = x(2);

Otherwise, no inputs will affect the output xdot.

[dpb]

In future, paste actual code text, not figure. That way folks can edit directly rather than having to type everything from scratch.

Answer 1

[dpb]

As another wrote, looks like you transposed the LH and RH sides of the assignment of input argument x to local variables. Why not use the named variable dummy argument array internally as the local variable and Matlab array syntax as well?

function Cwdot=NonLin(t,Cw)
  Cwi=1;
  k=1.5;
  F=100;
  V=[400; 2000];
  Cw=Cw(:);      % ensure column vector
  Cwdot=F./V.*(Cwi-Cw)-k*Cw.^2;
end