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why the code is not running?

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MINATI on 20 Dec 2018
Edited: madhan ravi on 28 Dec 2018
m = 0;
x = linspace(0,1,41);
t = linspace(0,200,10);
sol = pdepe(m,@pdex5pde,@pdex5ic,@pdex5bc,x,t);
n = sol(:,:,1);
c = sol(:,:,2);
title('Distribution of fibronectin--c(x)');
xlabel('Distance x');
ylabel('Time t');
title('Distribution of ECs--n(x)');
xlabel('Distance x');
ylabel('Time t');
title('Final distribution of n(x).');
title('Final distribution of c(x).');
% --------------------------------------------------------------------------
function [c,f,s] = pdex5pde(x,t,u,DuDx)
d = 1e-3;
a = 3.8;
S = 3;
r = 0.88;
N = 1;
c = [1; 1];
f = [ d*DuDx(1) - a*u(1)*DuDx(2)
DuDx(2) ];
s1 = S*r*u(1)*(N - u(1));
s2 = S*(u(1)/(u(1) + 1) - u(2));
s = [s1; s2];
% --------------------------------------------------------------------------
function u0 = pdex5ic(x)
u0 = [1; 0.5];
if x >= 0.3 & x <= 0.6
u0(1) = 1.05 * u0(1);
u0(2) = 1.0005 * u0(2);


Walter Roberson
Walter Roberson on 27 Dec 2018
Which MATLAB release are you using?
Walter Roberson
Walter Roberson on 28 Dec 2018
What shows up for
which -all pdepe
I have tried the example in R2016b, and I tried your code (along with a copy of pdex4bc renamed pdex5bc) in R2016b, and I do not get any problem about too many input arguments for pdepe. I do get the error that Cris mentioned: with that boundary condition, your sol comes out 1 x 41 and you cannot surf() a vector.
You should post the pdex5bc that you are using.

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Accepted Answer

Cris LaPierre
Cris LaPierre on 20 Dec 2018
Edited: Cris LaPierre on 25 Dec 2018
The pdex4 variable sol is a 9x13x2, or length(t) x length(x) x 2. The provided code (pdex5?) is 1x41x2. I don't understand your equations, but it looks like your code can't get past the t=0 step.
Can you double check that there is a solution at t=0?
It's worth verifying that your equations have been correctly entered as well.


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