MATLAB: Do I get the error ” too many input argument”

pdepe

I'm try to define the stepchange of bc in pdepe which pl varies with time. The following is my code.
Can anyone help? plzzzz…
T = 16;                    % maximum time [s]
L = 8;                     % length [m] 
D = 0.1;                   % diffusivity [m*m/s]
v = 0.5;                   % real fluid velocity [m/s]
theta = 0.2;               % porosity
rhob = 1200;               % porous medium bulk density [kg/m*m*m]
kappaf = 0.00;             % transition rate fluid to solid [1/s]
kappas =0.1;            % transition rate solid to fluid [1/s]
lambdaf = 0;               % decay rate in fluid [1/s]
lambdas = 0;               % decay rate in solid [1/s]
c0f = 1;                  % initial concentration in fluid [kg/m*m*m]
c0s = 0.1;                  % initial concentration in solid [1]
M = 100;                    % number of timesteps  (>2)
N = 40;                   % number of nodes
%-------------------------- output parameters------------------------------
gplot = 1;                 % =1: breakthrough curves; =2: profiles   1
t = linspace (T/M,T,M);    % time discretization
x = linspace (0,L,N);      % space discretization
cin = 10;                    % inflow concentration [kg/m*m*m]
bctimes=[0,5,5.1,T];
bcVals=[cin,cin,0,0];
%----------------------execution-------------------------------------------
bcFunc=@(xl,ul,xr,ur,t) slowsorpbc(xl,ul,xr,ur,t,bctimes,bcVals);
options = odeset;
c = pdepe(0,@slowsorpde,@slowsorpic,bcFunc,x,t,options,D,v,theta,rhob,kappaf,kappas,lambdaf,lambdas,[c0f;c0s]);
%---------------------- graphical output ----------------------------------
Y=c(:,N,1);
switch gplot
    case 1 
        plot (t,c(:,N,1))        % breakthrough curves
        xlabel ('time'); ylabel ('concentration');
    case 2 
        plot (x,c(:,:,2)','--')      % profiles
        xlabel ('space'); ylabel ('concentration');
end
% --------------------------------------------------------------------------


function [c,f,s] = slowsorpde(x,t,u,DuDx,D,v,theta,rhob,kappaf,kappas,lambdaf,lambdas,c0)
c = [1;1];
f = [D;0].*DuDx;
s = -[v;0].*DuDx - [lambdaf;lambdas].*u - ([kappaf,-kappas]*u)*[1/theta;-1/rhob];
end
% --------------------------------------------------------------------------
function u0 = slowsorpic(x,D,v,theta,rhob,kappaf,kappas,lambdaf,lambdas,c0)
u0 = c0;
end
    
% --------------------------------------------------------------------------
function [pl,ql,pr,qr] = slowsorpbc(xl,ul,xr,ur,t,bctimes,bcVals)
pl = [ul(1)-interp1(bctimes,bcVals,t);0];
ql = [0;1];
pr = [0;0];
qr = [1;1];
end

Best Answer

Although it is no longer documented, for backwards compatibility, if you pass extra arguments to pdepe(), then it attempts to pass those extra arguments to every function it invokes your your behalf.
You are passing the 9 extra arguments D, v, theta, rhob, kappaf, kappas, lambdaf, lambdas, [c0f;c0s] so your bcFunc and other functions that you pass in need to accept 9 extra input arguments besides what they normally take. So in the case of bcFunc which expects 5 inputs normally, the function handle you supply would have to accept 5+9 = 14 input arguments.
It is not recommended that you write any new code taking advantage of this old feature. There are already some subtle incompatibilities between it and some functions such as fmincon about what is expected to happen if you try to take advantage of leaving off some trailing inputs to the major function being invoked, but at the same time want to pass in extra inputs to the function handles.
The recommended approach is to instead parameterize your functions as needed, and not pass any extra arguments to pdepe using the undocumented feature.
You already have a good example of parameterization:
bcFunc=@(xl,ul,xr,ur,t) slowsorpbc(xl,ul,xr,ur,t,bctimes,bcVals);
That is a generally a good design.
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