Why does matlab request me to define a for-loop indexing term?

Hi everyone,

I am trying to run the attached code, but matlab gives this error:

Undefined function or variable 'k'.

Error in SlurryCaseODE45Feb18>DifEq (line 212)
        dcdt(1)            = (1/V_Headspace) * (F * CSO2_in - F * c(1) )- ((((c(1)*R*T - ((c(3)*CH(k)^2)/(CH(k)^2 + KSO2*CH(k) + KSO2*KHSO3)) *
        HSO2))/((1/kga) + (HSO2/(1 + ((DCa2 .* c(5))/(DSO2 .* c(3)))) * kLa_SO2))));

Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

Error in ode45 (line 115)
  odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in SlurryCaseODE45Feb18 (line 142)
      [t,Cv]=ode45(@DifEq,tspan,c0,Options);

Why does matlab request me to define k?

Please help.

Answer 1

[Walter Roberson]

Variables defined inside one workspace are not visible inside another workspace (the function) unless they are specifically passed in or otherwise imported.

See paramfun

However, you have

        for k = 1: length(t)

      [t,Cv]=ode45(@DifEq,tspan,c0,Options);
      
        end

Even if you were to pass k in specifically for use, then you would have the problem that you are overwriting t and Cv each iteration of k, so you would be throwing away all of the results except the last one.

You also use tv in several plot statements but you have not assigned anything to tv anywhere.

[Dursman Mchabe]

Thanks a lot Walter. The code now runs without errors.