Cannot get these errors to clear.

>> solve_ODEs_CA3

Unrecognized function or variable 'Cto'.

Error in solve_ODEs_CA3/ODEs_CA3 (line 37)

CA = Cto*(Fa/Ft) * (To/T);

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 solve_ODEs_CA3 (line 4)

[V,y] = ode45(@ODEs_CA3,tspan,y0);

>>

function solve_ODEs_CA3()
    tspan = (0:0.01:1);
    y0 = [100 0 0 423];
    [V,y] = ode45(@ODEs_CA3,tspan,y0);
    plot(V,y(:,1),'-o',V,y(:,2),'-o',V,y(:,3),'-o')
    title('Temperature Profile');
    xlablel('V(dm^3)');
    ylabel('t(k)');
    legend('F_A','F_B','F_C','T');
    
    function output = ODEs_CA3 (~,y)
        Fa = y(1);
        Fb = y(2);
        Fc = y(3);
        T = y(4);
        
        
       deltaH1 = -20000;
       deltaH2 = -60000;
       CPA = 90;
       CPB = 90; 
       CPC = 180;
       Ua = 4000;
       Ta = 373;
       ER1 = 4000;
       ER2 = 9000;
       T0 = 423;            %Setting values for first set of variables 
       
       %Eq. for K1A and K2A
       K1A = 10*exp(ER1*((1/300)-(1/T)));
       K2A = 0.09*exp(ER2*((1/300)-(1/T)));
        
       %Eq. for FT
       Ft = Fa + Fb + Fc;
       
       %Eq. for CA, CB, CC
       CA = Cto*(Fa/Ft) * (To/T);
       CB = Cto*(Fb/Ft)*(To/T);
       CC = Cto*(Fc/Ft)*(To/T);
       
       %Eq. for RA1 and RA2
       RA1 = -K1A*CA;
       RA2 = -K2A*(CA)^2;
       
       %Eq. for dFa, DFb, and Dfc derivatives
       dFAdV = RA1 +RA2;
       dFBdV = -RA1;
       dFCdv = -(1/2)*(-RA2);
       
       %Derivative of dT eq.
       dTdV = (Ua*(Ta-T)+(-RA1)*(deltaH1)+(-RA2)*(-deltaH2))/((Fa*CPA)+(Fb*CPB)+(Fc+CPC));
       
       ouput = [dFAdV;dFBdV:dFCdV;dTdV];
       size(output)
    end
       
end
       
       

Answer 1

[Cris LaPierre]

Your equations for CA, CB, CC in ODEs_CA3 function use a variable Cto that has not been created or at least does not exist within the scope of that function. You either need to define it, or pass it in as input to the function.

[Abby Revoir]

I defined that. Now getting these:

Error using odearguments (line 18)

When the first argument to ode45 is a function handle, the tspan and

y0 arguments must be supplied.

Error in ode45 (line 115)

odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options,

varargin);

Error in solve_ODEs_CA3 (line 4)

[V,y] = ode45(@(V,C)ODEs_CA3(tspan,y0));

[Cris LaPierre]

Follow the syntax shown in the documentation for ode45:

[t,y] = ode45(odefun,tspan,y0)

It looks like your are using [V,y] = ode45(@(V,C)ODEs_CA3(tspan,y0));

Try this instead:

[V,y] = ode45(@ODEs_CA3,tspan,y0);

There are several other typos in your code, but once you fix those, your code runs and produces a figure (I had to make up a value for Cto so the code would run).

[Abby Revoir]

Okay awesome i did all that as well and fixed a few more typos. Now getting this :(

>> solve_ODEs_CA3

Unrecognized function or variable 'dFCdV'.

Error in solve_ODEs_CA3/ODEs_CA3 (line 54)

ouput = [dFAdV:dFBdV:dFCdV:dTdV];

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 solve_ODEs_CA3 (line 4)

[V,y] = ode45(@ODEs_CA3,tspan,y0);

[Steven Lord]

You define a variable dFCdv but then try to use a variable dFCdV. Lower-case v and upper-case V are not interchangeable.

dFCdv = -(1/2)*(-RA2);
ouput = [dFAdV:dFBdV:dFCdV:dTdV];

You also don't want to use the colon operator : here, you want to separate the variables with semicolons ;.

[Abby Revoir]

Okay, so i fixed all my typos i think and now get this:

>> solve_ODEs_CA3

ans =

1 0

Error using odearguments (line 95)

SOLVE_ODES_CA3/ODES_CA3 returns a vector of length 1, but the length of initial conditions vector is 4. The

vector returned by SOLVE_ODES_CA3/ODES_CA3 and the initial conditions vector must have the same number of

elements.

Error in ode45 (line 115)

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

Error in solve_ODEs_CA3 (line 4)

[V,y] = ode45(@ODEs_CA3,tspan,y0);

[Cris LaPierre]

Use semicolons to create your output variable.

output = [dFAdV;dFBdV;dFCdV;dTdV];

[Abby Revoir]

It finally worked!! Thank you!!!!