Not enough input arguments

Hi there, I was running the spiral.m script in my computer and getting the following error.

Not enough input arguments.

"Error in spiral (line 19)
h = 2*L/n;"

My code:

function [T,W] = Spiral(n,L,Tend,nplots,D,e)
% function [T,Y] = Spiral(n,L,Tend,nplots,D,e)
% nominal usage: [T,Y] = Spiral(128,8,50,20,0.1,0.1)
% method of lines finite difference approximation for 
% Fitzhugh-Nagumo equations, periodic domain
% Input:   n is number of subintervals across domain
%          L is half-width of domain, -L<x,y<L
%          Tend is the end time, 0<t<Tend
%          nplots is the number during the time interval (nplots+1 if t=0
%                 included)
%          D is diffusivity (try 1,0.5,0.25,0.1)
% Output:  T is time levels for answer (nplots+1)
%          Y is the answer at T, needs to be reshaped to n+1 by n+1 grid

b = 0.67;
%e = 1;
%D = 0.1;

h = 2*L/n;
x = -L + h*(0:n)';                      % includes boundary
y = x;
[X,Y] = ndgrid(x,y);
Xi = X(1:n,1:n);  Yi = Y(1:n,1:n);      % interior points + one boundary

% set up ICS 
u = 5*ones(n,1)*([1:n]-0.4*n)/n;
v = 5*(([1:n]-0.4*n)')*ones(1,n)/n;
y0(1:n^2,1) = reshape(u,n^2,1);
y0(n^2+1:2*n^2,1) = reshape(v,n^2,1);
w=y0;

% Set up the one-dimensional 2nd-derivative matrices.
Dxx = toeplitz( [-2 1 zeros(1,n-2)]/h^2 );
Dxx(1,n) = 1; Dxx(n,1) = 1;  % periodic box case 
Dxx = sparse(Dxx);
Dyy = Dxx;

% Form discrete Laplacian.
I = speye(n);
A = sparse(kron(Dxx,I) + kron(I,Dyy));

MyTols = odeset('RelTol',1e-4,'AbsTol',1e-5);
[T,W] = ode45(@(t,u) rhs(t,u,A,D,b,e,n),[0:Tend/20:Tend],y0,MyTols);

for ii = 1:length(T)
    u = reshape(W(ii,1:n^2),n,n);
    max(max(u))
    v = reshape(W(ii,n^2+1:2*n^2),n,n);
    figure
    % colormap(hot); axis image off;
    %surface(Xi,Yi,u)
    colormap(hsv), pcolor(u)
    pause(1)
end

function dydt = rhs(t,z,A,D,b,e,n)
% right-hand side.
u1 = z(1:n^2,1);
u2 = z(n^2+1:2*n^2,1);
dydt = z;
dydt(1:n^2,1) = D*(A*u1)+(u1-u1.^3/3-u2)/e;
dydt(n^2+1:2*n^2,1) = e*(u1-u2/2+b);
end

end

What should I do now?

Best Regards

Zillur

[Tamir Suliman]

please upload the code or fix the formatting I dont know which is commented out and which is not

Answer 1

[Image Analyst]

Why don't you step through it with the debugger? We can't run your code because you didn't supply us with values for the input arguments n,L,Tend,nplots,D,& e. What did you pass in for those?

Say, you didn't just try to run the program by typing F5 or clicking the green run triangle, without passing in values, did you? Of course, you can't do that. What could it possibly use for n,L,Tend,nplots,D, & e? It can't just guess. You have to tell it.