MATLAB 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.