Keep getting error message on my ODE function

Question

Kristin Cynthia Hansel 2019-11-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/493416-keep-getting-error-message-on-my-ode-function

回答： Kristin Cynthia Hansel 2019-12-2

I am currently working on coding polymerization of PLA in a batch reactor keep getting error message. My professor helped my group get to this point but eveytime we run it we get,

Error using horzcat

Dimensions of arrays being concatenated are not consistent.

We have tried everything we can think of to fix this problem but we arent sure why this is happening or how to fix it.

Error in sad_girl_Project (line 46)

u0=[P0 zeros(N,1) 0] ;

function sad_girl_Project
T = 180+273.15; %Temperature [K]
Keq=10;
 
%% Calculations
lk1=-(6810.3/T)+6.1928
k1=exp(lk1) %rate constant for Polymerization (L/mol*s)
km1=k1/Keq %rate constant for depolymerization (L/mol*s)
P0=10;
N=100; %degree of polimerzation
% u=[P1, P2, .... PN, W]
function dudt=deq(t,u)
    
    P= u(1:N);
    W= u(N-1);
    sum3= sum(P);
 
    sum4=0;
    for ii=1:N
    
        sum1 = 0;
        for jj=1:ii-1
            sum1= sum1 + P(ii-jj)*P(jj);
        end % for jj
 
        %disp([ii, P(1:2), sum1])
 
        sum2= sum(P(ii+1:N));
        
        dudt(ii)= k1*sum1 + 2*km1*W*sum2 -             ...
                  2*k1*P(ii)*sum3 - km1*W*(ii-1)*P(ii);
                  
        sum4 = sum4 + (ii-1)*P(ii);
        
        %disp([ii, sum1, sum2 sum3])
        
    end % for ii
    
    dudt(N+1)= k1*sum3^2 - km1*W*sum4;
    dwdt(N+1)=0;
    
    dudt=[dudt; dwdt];
    
end % deq    
m=[0 24*3600] ;
u0=[P0 zeros(N,1) 0] ;
[t,u]=ode15(@deq,m,u0) ;
 
 
    %% Plot
figure(1)
plot(t,u)
title('Time Vs. Molecular Weight')
xlabel('Time []')
ylabel('Concentration []')
end

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darova 2019-11-27

在 MATLAB Online 中打开

DId you try to change the name of a function?

function happy_girl_Project

How do you want u0 vector should looks like?

u0=[P0 zeros(N,1) 0] ;
% P0 = 10;
% zeros(N,1) - column vector
% 0 = 0

Jan 2019-11-28

I've formatted the text and the code to improve the readability.

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Answer 1

Jan 2019-11-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/493416-keep-getting-error-message-on-my-ode-function#answer_403798

在 MATLAB Online 中打开

u0 = [P0, zeros(1, N + 1)];

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darova 2019-11-28

it works

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Answer 2

Kristin Cynthia Hansel 2019-12-2

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/493416-keep-getting-error-message-on-my-ode-function#answer_404180

Thank you!

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