too many input arguments when using pdepe

Hi, I meet a problem when using pdepe, and I tried many ways but can't solve this. Could you help me with this?

I got errors like 'too many/ not enough argument when using pdepe' when modifying

sol = pdepe(m,@(t,u) wave_ode1(x,t,u,dudx,p),@pdeic2,@pdebc2,x);

my code is below:

Thank you!

clear all
close all

hx = 0.1;%need try 0.01
L = 10;%
x = 0:hx:L;
t = [0:0.1:200];

Da=0.1;
Db=10;

m = 0;
p=[Da;Db];
sol = pdepe(m,@(t,u) wave_ode1(x,t,u,dudx,p),@pdeic2,@pdebc2,x);

u1 = sol(:,:,1);
u2 = sol(:,:,2);


surf(x,t,u1)
title('u_1(x,t)')
xlabel('Distance x')
ylabel('Time t')

surf(x,t,u2)
title('u_2(x,t)')
xlabel('Distance x')
ylabel('Time t')

function [c,f,s] = wave_ode1(x,t,u,dudx,p) % Equation to solve
c = [1; 1];
f = [Da; Db] .* dudx;
y = u(1) - u(2);
F = exp(5.73*y)-exp(-11.47*y);
s = [-F; F];
end


function u0 = pdeic2(x) % Initial Conditions
u0 = [1; 0];
end


function [pl,ql,pr,qr] = pdebc2(xl,ul,xr,ur,t) % Boundary Conditions
pl = [0; ul(2)];
ql = [1; 0];
pr = [ur(1)-1; 0];
qr = [0; 1];
end

Answer 1

[Torsten]

sol = pdepe(m,@(x,t,u,dudx) wave_ode1(x,t,u,dudx,p),@pdeic2,@pdebc2,x,t);

function [c,f,s] = wave_ode1(x,t,u,dudx,p) % Equation to solve
c = [1; 1];
f = [p(1); p(2)] .* dudx;
y = u(1) - u(2);
F = exp(5.73*y)-exp(-11.47*y);
s = [-F; F];
end

[ZIYI LIU]

Hi Torson, this works for me! Thank you very very much!

Could you help me with another question please? Also with this code.

The problem is that there is a stimuli in the system which denpends in x and t, for example:

(But the code has errors)

function [c,f,s] = wave_ode1(x,t,u,dudx,p) % Equation to solve

c = [1; 1];

f = [p(1); p(2)] .* dudx;

y = u(1) - u(2);

ss=piecewise((0<= t) & (t <= 20),0.05/2,(20< t) & (t <= 25),0.05/4*(1+cos(pi*(t-20)/(25-20))),0);

ks=piecewise((0<= x) & (x <= 1),ss*(1+cos(pi*x)),1);

F = exp(5.73*y)-exp(-11.47*y)+ks;

s = [-F; F];

end

[Torsten]

if x <= 1  
  if t <= 20
    ss = 0.05/2;
  elseif t > 20 && t <= 25
    ss = 0.05/4*(1+cos(pi*(t-20)/(25-20)));
  else
    ss = 0;
  end
  ks = ss*(1+cos(pi*x));
else
  ks = 1.0;
end

[ZIYI LIU]

Hi Torsten, thank you very much! But I still met an error like ' The function "pdebc" was closed with an 'end', but at least one other function definition was not. All functions in a script must be closed with an 'end'.'. My modified code is below:

function [c,f,s] = wave_ode1(x,t,u,dudx,p) % Equation to solve
Da=p(1);
Db=p(2);
c = [1; 1];
f = [Da; Db] .* dudx;
y = u(1) - u(2);
if t <= 20
    ss = 0.05/2;
  else if t > 20 && t <= 25
    ss = 0.05/4*(1+cos(pi*(t-20)/(25-20)));
  else
    ss = 0;
  end
  
  if x <= 1
    ks = ss*(1+cos(pi*x));
  else
    ks = 1.0;
  end
F = exp(5.73*y)-exp(-11.47*y)+ks;
s = [-F; F];
end

[Torsten]

elseif

instead of

else if

[ZIYI LIU]

Hi Torsten, I modified little based on your code and it works for me! Thank you so much!

function [c,f,s] = wave_ode1(x,t,u,dudx,p) % Equation to solve
Da=p(1);
Db=p(2);
c = [1; 1];
f = [Da; Db] .* dudx;
y = u(1) - u(2);
if t <= 20
    ss = 0.05/2;
  elseif t > 20 && t <= 25
    ss = 0.05/4*(1+cos(pi*(t-20)/(25-20)));
  else
    ss = 0;
end
  
if x <= 1
    ks = ss*(1+cos(pi*x));
  else
    ks = 1.0;
end

F = exp(5.73*y)-exp(-11.47*y)+ks;
s = [-F; F];
end

Answer 2

[Walter Roberson]

sol = pdepe(m,@(t,u) wave_ode1(x,t,u,dudx,p),@pdeic2,@pdebc2,x);

pdepe needs m, then three function handles, then x mesh, and then time span.

You have m, then three function handles, then x mesh... and no time span.

[ZIYI LIU]

Hi Walter, I add t, but still have error said

'Error in wave (line 14)

sol = pdepe(m,@(t,u) wave11(x,u,dudx,p),@pdeic1,@pdebc1,x,t);'

[Walter Roberson]

The pdefun (first function handle) will be passed x, t, u, dudx. Your @(t,u) function handle expects to receive only two parameters.