MATLAB: I am a bigenner in matlab, I got this message when I am trying to run the code: Error using / Matrix dimensions must agree.

function fx = tubular4 (time,y)
global n length
global alpha beta
c = y';
%









% boundary condition @ x = 0
%
cz = (1/alpha)*(c(1)-1);
%
% boundary condition @ x = 1
%
cz (n) = 0;
%
% Direct second order derivative czz (diffusional term)
%
czz = dss044 (0,length,n,c,cz,2,2);
%
% first order derivarive (convective term)
%
cz = dss020 (0,length,n,c,1);
%
% return the discretized value of the math model
%
fx = [alpha*czz-cz-beta*c.^2]';
%-- End of the tubular4.m file --

Best Answer

Dear mr Image analyst, I tired your suggestions but the problem is still appear:

Error using  /   Matrix dimensions must agree.
Error in dss044 (line 24)
r12dxs = 1. /(12.*dx^2);
Error in tubular4 (line 17)
czz = dss044 (0,length,n,c,cz,2,2);
Error in odearguments (line 88)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.
Error in ode15s (line 149)
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...
Error in Untitled4 (line 31)
[timea,conca] = ode15s('tubular4',tspan,cic);

Related Solutions

MATLAB: Index in position 1 exceeds array bounds (must not exceed 301) and Error in IMR_2psv (line 34) u(i,:)=(1/16)(-u(i-2,:)+4u(i-1,:)+10u(i,:)+4u(i+1,:)-u(i+2,:));

Your last loop go one step too far. u is 301x151 and n = 300. Then u(n+2) exceeds array bounds.

clear;
Lmax = 1.0; % Maximum length
Tmax = 1.; % Maximum time
c = 1.0; % Advection velocity
maxt = 150; % Number of time steps
dt = Tmax/maxt;
n = 300; % Number of space steps
nint=15; % The wave-front: intermediate point from which u=0
dx = Lmax/n;
b = c*dt/(2.*dx);
for i = 1:(n+1)
    if i < nint
        u(i,1)=1.;
    else
        u(i,1)=0.;
    end
    x(i) =(i-1)*dx;
end
for k=1:maxt+1
    u(1,k) = 1.;
    u(n+1,k) = 0.;
    time(k) = (k-1)*dt;
end
for k=1:maxt % Time loop
    for i=3:n-1 % Space loop
        u(i,:)=(1/16)*(-u(i-2,:)+4*u(i-1,:)+10*u(i,:)+4*u(i+1,:)-u(i+2,:));
    end
end

MATLAB: Solving linear convection equation (wave equation) by Lax Wendroff Scheme

N=100; %No. of grid points
Tmax=1; % time period=1
alpha=1;  %given
h=0.01; %given value of delX
delt=0.005;
maxt=Tmax/delt; %Number of time steps
c=alpha*delt/h; %c=0.5
u=zeros(N+1,maxt+1);
x=zeros(N+1,1);
% Initial condition
for i=1:N+1
  x(i)=(i-1)*h;
  u(i,1)=sin(2*pi*x(i));
end
for k=1:maxt
  u0 = u(N,k);
  u(1,k+1)=u(1,k)-c/2*(u(2,k)-u0)+c^2/2*(u(2,k)-2*u(1,k)+u0);
  for i=2:N
    u(i,k+1) =u(i,k)-c/2*(u(i+1,k)-u(i-1,k))+(c^2)/2*(u(i+1,k)-2*u(i,k)+u(i-1,k));
  end
  uNp2 = u(2,k);
  u(N+1,k+1) =u(N+1,k)-c/2*(uNp2-u(N,k))+c^2/2*(uNp2-2*u(N+1,k)+u(N,k));  
end
plot(x,u(:,10),x,u(:,20),x,u(:,30),x,u(:,40),x,u(:,50),x,u(:,60),x,u(:,70))

Best Answer

Related Solutions

MATLAB: Index in position 1 exceeds array bounds (must not exceed 301) and Error in IMR_2psv (line 34) u(i,:)=(1/​16)*(-u(i-​2,:)+4*u(i​-1,:)+10*u​(i,:)+4*u(​i+1,:)-u(i​+2,:));

MATLAB: Solving linear convection equation (wave equation) by Lax Wendroff Scheme

Related Question

MATLAB: Index in position 1 exceeds array bounds (must not exceed 301) and Error in IMR_2psv (line 34) u(i,:)=(1/16)(-u(i-2,:)+4u(i-1,:)+10u(i,:)+4u(i+1,:)-u(i+2,:));