why the code is not running?

2018 12 20
1 个回答
回答已采纳
更新时间：2018 12 28
8 次查看（30 天）

1 个投票

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

13 个评论
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Walter Roberson
Walter Roberson 2018-12-20
What error message are you getting?
madhan ravi
madhan ravi 2018-12-20
编辑：madhan ravi 2018-12-28
Upload pdex5bc function.
KSSV
KSSV 2018-12-20
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
MINATI 2018-12-20
Error using pdepe
Too many input arguments.
Error in pdex5
sol = pdepe(m,@pdex5pde,@pdex5ic,@pdex5bc,x,t);
Stephen23
Stephen23 2018-12-20
@MINATI: please show us the output from this command:
which pdepe -all
MINATI
MINATI 2018-12-20
try
edit pdex5
Cris LaPierre
Cris LaPierre 2018-12-20
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
madhan ravi 2018-12-20
编辑：madhan ravi 2018-12-20
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
MINATI 2018-12-27
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
Walter Roberson 2018-12-27
Which MATLAB release are you using?
Walter Roberson
Walter Roberson 2018-12-28
编辑：Walter Roberson 2018-12-28
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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 采纳的回答

Cris LaPierre
Cris LaPierre 2018-12-20
编辑：Cris LaPierre 2018-12-25

0 个投票

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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