Using a loop with changing intial value

I need to use a loop to be used to solve the ODE with various T0 which needs to range from 300 to 800. Right now i only know how to do one T0 at a time, but i need to evalute all from 300 to 800. Please help.

% Initial conditions
Ca0 = 2;
Cb0 = 4;
Cc0 = 0;
Cd0 = 0;
T0  = 600;
IC = [Ca0 Cb0 Cc0 Cd0 T0];
% V range
Vspan = [0 10];
% Call ode solver
[V, CT] = ode45(@fn, Vspan, IC);
% Extract parameters
 Ca = CT(:,1);
 Cb = CT(:,2);
 Cc = CT(:,3);
 Cd = CT(:,4);
 T  = CT(:,5);
 
 % Plot graphs
 figure
 plot(V,Ca,V,Cb,V,Cc,V,Cd),grid
 xlabel('V (dm^3)'),ylabel('Ca.Cb.Cc,Cd (mol/dm^3)')
 legend('Ca','Cb','Cc','Cd')
 
 figure
 plot(V,T),grid
 xlabel('V(dm^3)'),ylabel('T(K)')
% ODE function
function dCTdV = fn(~,CT)
        % Data
        Cpa = 20;
        dh1a = 20000;
        dh2a = -10000;
        vo = 10;
        % Extract parameters
         Ca = CT(1);
         Cb = CT(2);
         Cc = CT(3);
         Cd = CT(4);
         T  = CT(5);
         
        % k and r functions
        k1a = 0.001*exp(-5000/1.987*(1/T - 1/300));
        k2a = 0.001*exp(-7500/1.987*(1/T - 1/300));
        r1a = -k1a*Ca*Cb^2;
        r2a = -k2a*Ca*Cc;
         % odes
         dCTdV = [(r1a+r2a)/vo;
                   2*r1a/vo;
                   (-2*r1a+r2a)/vo;
                   -2*r2a/vo;
                   (r1a*dh1a + r2a*dh2a)/((Ca+Cb+3*Cc+4*Cd)*vo*Cpa)];
end

Answer 1

[David Hill]

% Initial conditions
Ca0 = 2;
Cb0 = 4;
Cc0 = 0;
Cd0 = 0;
T0  = 300:100:800;
IC = [repmat([Ca0 Cb0 Cc0 Cd0],length(T0),1),T0'];
% V range
Vspan = [0 10];
% Call ode solver
for k=1:size(IC,1)
 [V{k}, CT{k}] = ode45(@fn, Vspan, IC(k,:));
 figure;
 plot(V{k},CT{k}(:,1),V{k},CT{k}(:,2),V{k},CT{k}(:,3),V{k},CT{k}(:,4));
 xlabel('V (dm^3)'),ylabel('Ca.Cb.Cc,Cd (mol/dm^3)');
 legend('Ca','Cb','Cc','Cd');
 figure
 plot(V{k},CT{k}(:,5));
 grid on;
 xlabel('V(dm^3)'),ylabel('T(K)');
end
 
% ODE function
function dCTdV = fn(~,CT)
        % Data
        Cpa = 20;
        dh1a = 20000;
        dh2a = -10000;
        vo = 10;
        % Extract parameters
         Ca = CT(1);
         Cb = CT(2);
         Cc = CT(3);
         Cd = CT(4);
         T  = CT(5);
         
        % k and r functions
        k1a = 0.001*exp(-5000/1.987*(1/T - 1/300));
        k2a = 0.001*exp(-7500/1.987*(1/T - 1/300));
        r1a = -k1a*Ca*Cb^2;
        r2a = -k2a*Ca*Cc;
         % odes
         dCTdV = [(r1a+r2a)/vo;
                   2*r1a/vo;
                   (-2*r1a+r2a)/vo;
                   -2*r2a/vo;
                   (r1a*dh1a + r2a*dh2a)/((Ca+Cb+3*Cc+4*Cd)*vo*Cpa)];
end

[Will Jeter]

i get an error that says, "Unable to perform assignment because brace indexing is not

supported for variables of this type."

[David Hill]

Did you copy and paste it into script and run it? Works fine for me.

[Will Jeter]

yeah i did and all i get is this

Unable to perform assignment because brace indexing is not
supported for variables of this type.

Error in yrhtd (line 12)
 [V{k}, CT{k}] = ode45(@fn, Vspan, IC(k,:));

[David Hill]

Make sure your workspace is clear. It should work.

clear;