Can't run my main Matlab file related to ODE solution

[Ein Krieger]

Hey, guys

Can you please help me to spot mistakes in numerical solution of following diffusivty equation:

∂P/∂t= 0.001127*k/(μ*ϕ*c_t )*((∂P/∂x)^2*c+(∂^2 P)/(∂x^2 )).

Matlab give the following command:

Undefined function or variable 'r'.

Error in function_handle2 (line 9)
for i=1:r

Error in odearguments (line 88)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode15s (line 149)
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Error in Diffusivity_equation (line 41)
[t,p]=ode15s(@function_handle2,tout,p0,options);


I don't know how to interpret the last command. M files containing relevant commands are attached.

 

[DrClaude]

I get an error on line 10 of function_handle2. When I comment it out, I get an error because dss004 is undefined.

 

[Ein Krieger]

I get an error on line 10 of function_handle2. When I comment it out, I get an error because dss004 is undefined.

Hey, mate

You can download dss004 m file from the following link:
https://www.physicsforums.com/showthread.php?p=4292439#post4292439.

I couldn't upload the dss004 file, so decided to redirect you to my previous post where I have already atttached dss004.

 

[Ein Krieger]

Guys, I need to solve by Matlab the following PDE:

I am desperate about finding solution; I have tried many approaches, and the files attached on topic start is my last approach.

 

[alphy]

Hello,

I'm sorry to hear that you are having trouble running your main Matlab file related to ODE solution. It seems like you are encountering an error message related to an undefined function or variable 'r'. This could be due to a number of reasons, such as a typo in your code or a missing variable declaration.

To help you spot the mistake, I would recommend checking the code for any typos or missing variables. You can also try debugging your code by running it step by step to see where the error occurs.

Additionally, it would be helpful if you could provide more information about your code and the specific error message you are receiving. This will allow me to provide more specific suggestions and assistance.

I hope this helps and good luck with your code!