why the code is not running?

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);

figure;
surf(x,t,c);
title('Distribution of fibronectin--c(x)');
xlabel('Distance x');
ylabel('Time t');

figure;
surf(x,t,n);
title('Distribution of ECs--n(x)');
xlabel('Distance x');
ylabel('Time t');

figure;
plot(x,n(end,:));
title('Final distribution of n(x).');

figure;
plot(x,c(end,:));
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);
end

[Walter Roberson]

What error message are you getting?

[madhan ravi]

Upload pdex5bc function.

[KSSV]

YOu should specify your error or problem..so that we can help you straight away if possible. Simply copying a part of code will not help us to help you.

[MINATI]

Error using pdepe

Too many input arguments.

Error in pdex5

sol = pdepe(m,@pdex5pde,@pdex5ic,@pdex5bc,x,t);

[Stephen23]

@MINATI: please show us the output from this command:

which pdepe -all

[MINATI]

try

edit pdex5

[madhan ravi]

?

[Cris LaPierre]

Based heavily on this example (scroll to the 2nd example), for those trying to debug

function pdex4
m = 0;
x = [0 0.005 0.01 0.05 0.1 0.2 0.5 0.7 0.9 0.95 0.99 0.995 1];
t = [0 0.005 0.01 0.05 0.1 0.5 1 1.5 2];

sol = pdepe(m,@pdex4pde,@pdex4ic,@pdex4bc,x,t);
u1 = sol(:,:,1);
u2 = sol(:,:,2);

figure
surf(x,t,u1)
title('u1(x,t)')
xlabel('Distance x')
ylabel('Time t')

figure
surf(x,t,u2)
title('u2(x,t)')
xlabel('Distance x')
ylabel('Time t')
% --------------------------------------------------------------
function [c,f,s] = pdex4pde(x,t,u,DuDx)
c = [1; 1]; 
f = [0.024; 0.17] .* DuDx; 
y = u(1) - u(2);
F = exp(5.73*y)-exp(-11.47*y);
s = [-F; F]; 
% --------------------------------------------------------------
function u0 = pdex4ic(x);
u0 = [1; 0]; 
% --------------------------------------------------------------
function [pl,ql,pr,qr] = pdex4bc(xl,ul,xr,ur,t)
pl = [0; ul(2)]; 
ql = [1; 0]; 
pr = [ur(1)-1; 0]; 
qr = [0; 1];

If I straight borrow pdex4bc and add it to the code provided above, I get the following warnings/errors:

• Warning: Failure at t=1.269576e-02. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.775558e-17) at time t.
• Warning: Time integration has failed. Solution is available at requested time points up to t=1.000000e-02.
• Error using surf (line 71)
• Data dimensions must agree.

[madhan ravi]

Well thank you Cris for digging into a bit deeper , @Minati just two words doesn’t explain anything , you need to explain more plus you completely ignored the comments which were latter to your comment.

[MINATI]

But Cris

If we run this program:

Error using pdepe

Too many input arguments.

in

sol = pdepe(m,@pdex4pde,@pdex4ic,@pdex4bc,x,t);

[Walter Roberson]

Which MATLAB release are you using?

[MINATI]

2016b

[Walter Roberson]

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.

Answer 1

[Cris LaPierre]

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.