Why doesn't M2 function get called? Could somebody please explain what this error is and how to fix it?

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cindyawati cindyawati 2023-6-17

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https://ww2.mathworks.cn/matlabcentral/answers/1984614-why-doesn-t-m2-function-get-called-could-somebody-please-explain-what-this-error-is-and-how-to-fix

评论： cindyawati cindyawati 2023-6-20

I have function for M2

function M2 =fRK4M2(M1,M2)
M1=10;
M2=0;
mu_2=10^-3;
K1= 10^-4;
K2=5*10^-4;
M2 = (K1*M1*M1)-(K2*M1*M2)-(mu_2*M2);

This is my M1 function

function M1 =fRK4M1(M1,M2,M3,O,P)  
  delta=50;
  K1= 10^-4;
  Ko=0.1;
  n=3;
  Oa=10;
  Pa=100;
  mu_1=10^-3;
  K2=5*10^-4;
  K3=10^-3;
  gamma=75;
 
  M1=(delta*M1*(1-(M1/gamma))-2*K1*M1*M1-M1*(K2.*M2)-((Oa-n)*K3*M1*M3)-((Pa-Oa)*Ko*M1*O)-(mu_1*M1)); 
    

And this is my main function

clc;clear;
  
%input for time
t(1)=0;
dt=0.1; %time interval
t=0:dt:100; %time span
%input empty array
T=zeros(length(t),1); %empty array for t
M1=zeros(length(t),1); %empty array for M1
M2=zeros(length(t),1); %empty array for M2
for j = 1:length((t))
    T(j+1)=T(j)+dt;
    M1(j+1)= M1(j)+1./(1+exp(-T(j)));
   
    k1M2 = dt*fRK4M2(M2(j),M1(j));
    k2M2 = dt*fRK4M2(M2(j)+k1M2/2,M1(j)+k1M2/2);
    k3M2 = dt*fRK4M2(M2(j)+k2M2/2,M1(j)+k2M2/2);
    k4M2 = dt*fRK4M2(M2(j)+k3M2,M1(j)+k3M2/2);
    M2(j+1) = M2(j)+1/6*(k1M2+2*k2M2+2*k3M2+k4M2);
    
    k1M1= dt*fRK4M1(M1(j),M2(j));
    k2M1= dt*fRK4M1(M2(j)+k1M2/2,M1(j)+k1M1/2);
    k3M1= dt*fRK4M1(M2(j)+k2M2/2,M1(j)+k2M1/2);
    k4M1= dt*fRK4M1(M2(j)+k3M2/2,M1(j)+k3M1/2);
    M1(j+1) = M1(j)+(1/6*(k1M1+(2*k2M1)+(2*k3M1)+k4M1));
    end

the results I get are not as desired, please someone tell me my fault adn how to fix it. Thanks

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Torsten 2023-6-18

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So the task of your code is to solve the system of differential equations

dM1/dt = (delta*M1*(1-(M1/gamma))-2*K1*M1*M1-M1*(K2.*M2)-((Oa-n)*K3*M1*M3)-((Pa-Oa)*Ko*M1*O)-(mu_1*M1))
dM2/dt = (K1*M1*M1)-(K2*M1*M2)-(mu_2*M2)

?

Since your code has so many errors, I suggest you use ODE45 for the solution.

cindyawati cindyawati 2023-6-18

编辑：cindyawati cindyawati 2023-6-18

thank you for response @Torsten yes my code to solve the system of differential equation. If I use Runge Kutta orde 4th is it possible?

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Answer 1

Lakshya 2023-6-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1984614-why-doesn-t-m2-function-get-called-could-somebody-please-explain-what-this-error-is-and-how-to-fix#answer_1257864

Hi,

The code you provided initializes M1 and M2 to specific values (M1 = 10 and M2 = 0) within the fRK4M2 function, which might override the values passed as arguments. If you intend to use the passed arguments instead, you can remove those assignments from the fRK4M2 function.

Hope this helps.

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cindyawati cindyawati 2023-6-18

编辑：cindyawati cindyawati 2023-6-18

在 MATLAB Online 中打开

Hello @Lakshya I already input argument for M3,O, and P but my plot for M2, O and P not as expected ( I expected get like sigmoid graph). Why doesnt my graph show a sigmoid graph even though I have include in the main function? This is my main function

clc;clear;
  
%input for time
t(1)=0;
dt=0.1; %time interval
t=0:dt:100; %time span
%input empty array
T=zeros(length(t),1); %empty array for t
M1=zeros(length(t),1); %empty array for M1
M2=zeros(length(t),1); %empty array for M2
M3=zeros(length(t),1); %empty array for M3
O=zeros(length(t),1); %empty array for O
P=zeros(length(t),1); %empty array for P
 %initial condition
    M1 =10;
    M2 = 0;
    M3 = 0;
    O =0;
    P =0;
for j = 1:length((t))
    T(j+1)=T(j)+dt;
    M1(j+1)= M1(j)+1./(1+exp(-T(j)));
    
    k1M2 = dt*fRK4M2(M2(j),M1(j));
    k2M2 = dt*fRK4M2(M2(j)+k1M2/2,M1(j)+k1M2/2);
    k3M2 = dt*fRK4M2(M2(j)+k2M2/2,M1(j)+k2M2/2);
    k4M2 = dt*fRK4M2(M2(j)+k3M2,M1(j)+k3M2/2);
    M2(j+1) = M2(j)+1/6*(k1M2+2*k2M2+2*k3M2+k4M2);
    
    k1M3 = dt*fRK4M3(M1(j),M3(j));
    k2M3 = dt*fRK4M3(M3(j)+k1M3/2,M1(j)+k1M3/2);
    k3M3 = dt*fRK4M3(M3(j)+k2M3/2,M1(j)+k2M3/2);
    k4M3 = dt*fRK4M3(M3(j)+k3M3,M1(j)+k3M3);
    M3(j+1) = M3(j)+1/6*(k1M3+2*k2M3+2*k3M3+k4M3);
    
    k1O = dt*fRK4O(M1(j),O(j));
    k2O = dt*fRK4O(O(j)+k1O/2,M1(j)+k1O/2);
    k3O = dt*fRK4O(O(j)+k2O/2,M1(j)+k2O/2);
    k4O = dt*fRK4O(O(j)+k3O,M1(j)+k3O);
    O(j+1) = O(j)+1/6*(k1O+2*k2O+2*k3O+k4O);
    
    k1P = dt*fRK4P(P(j),M1(j));
    k2P = dt*fRK4P(P(j)+k1P/2,M1(j)+k1P/2);
    k3P = dt*fRK4P(P(j)+k2P/2,M1(j)+k2P/2);
    k4P = dt*fRK4P(P(j)+k3P,M1(j)+k3P/2);
    P(j+1) = P(j)+1/6*(k1P+2*k2P+2*k3P+k4P);
    
    k1M1= dt*fRK4M1(M1(j),M2(j),M3(j),O(j),P(j));
    k2M1= dt*fRK4M1(M2(j)+k1M2/2,M3(j)+k1M3/2,O(j)+k1O/2,P(j)+k1P/2,M1(j)+k1M1/2);
    k3M1= dt*fRK4M1(M2(j)+k2M2/2,M3(j)+k2M3/2,O(j)+k2O/2,P(j)+k2P/2,M1(j)+k2M1/2);
    k4M1= dt*fRK4M1(M2(j)+k3M2/2,M3(j)+k3M3/2,O(j)+k3O/2,P(j)+k3P/2,M1(j)+k3M1/2);
    M1(j+1) = M1(j)+(1/6*(k1M1+(2*k2M1)+(2*k3M1)+k4M1));
    end
Unrecognized function or variable 'fRK4M2'.
  
figure;
plot (T,M1,'r','Linewidth',3)
xlabel('time')
ylabel('M1')
figure 
plot (T,M2,'b','Linewidth',3)
xlabel('time')
ylabel('M2')
figure 
plot (T,M3,'g','Linewidth',3)
xlabel('time')
ylabel('M3')
figure 
plot (T,O,'b','Linewidth',5)
xlabel('time')
ylabel('O')
figure 
plot (T,P,'r','Linewidth',5)
xlabel('time')
ylabel('P')

This is my result plot. Why my O and P (P graph same like O graph) graph no changes

cindyawati cindyawati 2023-6-19

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No, I mean the code with Runge-Kutta orde 4. I input sigmoid function inside for looping before runge kutta. This is my code

clc;clear;
  
%input for time
t(1)=0;
dt=0.1; %time interval
t=0:dt:100; %time span
%input empty array
T=zeros(length(t),1); %empty array for t
M1=zeros(length(t),1); %empty array for M1
M2=zeros(length(t),1); %empty array for M2
for j = 1:length((t))
    T(j+1)=T(j)+dt;
    M1(j+1)= M1(j)+1./(1+exp(-T(j))); %this is sigmoid function
   
    k1M2 = dt*fRK4M2(M2(j),M1(j));
    k2M2 = dt*fRK4M2(M2(j)+k1M2/2,M1(j)+k1M2/2);
    k3M2 = dt*fRK4M2(M2(j)+k2M2/2,M1(j)+k2M2/2);
    k4M2 = dt*fRK4M2(M2(j)+k3M2,M1(j)+k3M2/2);
    M2(j+1) = M2(j)+1/6*(k1M2+2*k2M2+2*k3M2+k4M2);
    
    k1M1= dt*fRK4M1(M1(j),M2(j));
    k2M1= dt*fRK4M1(M2(j)+k1M2/2,M1(j)+k1M1/2);
    k3M1= dt*fRK4M1(M2(j)+k2M2/2,M1(j)+k2M1/2);
    k4M1= dt*fRK4M1(M2(j)+k3M2/2,M1(j)+k3M1/2);
    M1(j+1) = M1(j)+(1/6*(k1M1+(2*k2M1)+(2*k3M1)+k4M1));
    end
Unrecognized function or variable 'fRK4M2'.

This my function for M1, M2, M3, O, and P

function M2 =fRK4M2(M2,M1)
M1=10;
%M2=0;
mu_2=10^-3;
K1= 10^-4;
K2=5*10^-4;     
M2 = (K1*M1*M1)-(K2*M1*M2)-(mu_2*M2);
function M3 =fRK4M3(M3,M1)
%M1=10;
M2=0;
%M3=0;
mu_3=10^-3;
K2=5*10^-4;
K3=10^-3;
M3=(K2*M1*M2)-(K3*M1*M3)-(mu_3*M3);
function O =fRK4O(O,M1)
%M1=10;
M3=0;
O=0;
Ko=0.1;
mu_o=10^-4;
K3=10^-3;
O  = (K3*M1*M3)-(Ko*M1*O)-(mu_o*O);
function P =fRK4P(P,M1)
%M1=10;
O=0;
%P=0;
Ko=0.1;
mu_p= 10^-5;
P  = (Ko*M1*O)-(mu_p*P);
 
function M1 =fRK4M1(M1,M2,M3,O,P)  
  delta=50;
  K1= 10^-4;
  Ko=0.1;
  n=3;
  Oa=10;
  Pa=100;
  mu_1=10^-3;
  K2=5*10^-4;
  K3=10^-3;
  gamma=75;
 
  M1=(delta*M1*(1-(M1/gamma))-2*K1*M1*M1-M1*(K2.*M2)-((Oa-n)*K3*M1*M3)-((Pa-Oa)*Ko*M1*O)-(mu_1*M1)); 
    

cindyawati cindyawati 2023-6-19

Ok, I know where I went wrong when I used the 4th order Runge kutta formula. I tried removing the sigmoid function and my program is still running. But the Y-axis for M3 has a negative value and the O and P graphs remain flat. Why?

cindyawati cindyawati 2023-6-20

在 MATLAB Online 中打开

Hello @Torsten I wanna ask If I use ODE45 for my problem. I must make 5 function (M1,M2, M3,O,and P) for ODE45 in separate file or I make one file include 5 function? Btw I already try solve my code using ODE45 but i get error like this. How to fix it? Thank you

function CM1 = mymode (t,M1)
M1= 10; 
M2 = 0;
M3 = 0; 
O  = 0; 
P=0;
delta=50;
K1= 10^-4;
Ko=0.1;
n=3;
Oa=10;
Pa=100;
mu_1=10^-3;
K2=5*10^-4;
K3=10^-3;
gamma=75;
mu_2=10^-3;
mu_3=10^-3;
mu_o=10^-4;
mu_p= 10^-5;
CM1= zeros(2,1);
CM1(1) = (delta*M1*(1-(M1/gamma))-2*K1*M1*M1-M1*(K2*M2)-((Oa-n)*K3*M1*M3)-((Pa-Oa)*Ko*M1*O)-(mu_1*M1));
CM1(2) = (K1*M1*M1)-(K2*M1*M2)-(mu_2*M2);
CM1(3) = (K2*M1*M2)-(K3*M1*M3)-(mu_3*M3);
CM1(4) = (K3*M1*M3)-(Ko*M1*O)-(mu_o*O);
CM1(5) = (Ko*M1*O)-(mu_p*P);
[t,M1] = ode45(mymode, [0,100],[0,1])
plot (t,M1)
end
>> mymode
Out of memory. The likely cause is an infinite recursion within the program.
Error in mymode (line 31)
[t,M1] = ode45(mymode, [0,100],[0,1])

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Why doesn't M2 function get called? Could somebody please explain what this error is and how to fix it?

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