Index in position 4 exceeds array bounds (must not exceed 1).

for j = 2:ny-1
     for i = 2:nx-1      
            Ex(i,j,n,1) = 150; %initial guess
            Ey(i,j,n,1) = 200; %initial guess   
         for g = 1:gfinal-1    
            M11(i,j,n,g) = (1/(4*dt))*(g1+g2+g3)+(eps/dt)*(1+(alpha/kai0)*(3*(Ex(i,j,n+1,g))^2+(Ey(i,j,n+1,g))^2)+S(i,j,n+1));
            M22(i,j,n,g) = (1/(4*dt))*(g1+g2+g3)+(eps/dt)*(1+(alpha/kai0)*((Ex(i,j,n+1,g))^2+3*(Ey(i,j,n+1,g))^2)+S(i,j,n+1));
            M12(i,j,n,g) = ((2*eps)/dt)*alpha*kai0*Ex(i,j,n+1,g)*Ey(i,j,n+1,g);
            M21(i,j,n,g) = ((2*eps)/dt)*alpha*kai0*Ex(i,j,n+1,g)*Ey(i,j,n+1,g);
            M(:,:) = ([M11(i,j,n,g),M12(i,j,n,g); M21(i,j,n,g),M22(i,j,n,g)]);
            Minv(:,:) = inv([M11(i,j,n,g),M12(i,j,n,g); M21(i,j,n,g),M22(i,j,n,g)]);
            Ex(:,:,n+1,g+1) = Ex(:,:,n+1,g)- Minv(1,1)*X(i,j,n,g) - Minv(1,2)*Y(i,j,n,g);
                    if (abs(X(i,j,n)) <= tol && abs(Y(i,j,n)) <= tol)    
                        break;
                    end
                 Ex(i,j,n,g+1) = Ex(i,j,n);
            end 
     end
 end

Hello. I am trying to solve newton's method problem.

But there's an error after M11(i,j,n,g) line. 'Index in position 4 exceeds array bounds (must not exceed 1).'

Can you help me with that problem?

Thanks!

[James Tursa]

Do this at the command line:

dbstop if error

Then run your code. When the error appears the code will pause will all variables intact. Examine them to see what their actual dimensions are, and then backtrack in your code to figure out why they are not the size that you expect.

[Junseob Kim]

Thank you so much!

Answer 1

[Walter Roberson]

You define

Ex(i,j,n,1) = 150; %

but we have no reason to expect that on the line

            M11(i,j,n,g) = (1/(4*dt))*(g1+g2+g3)+(eps/dt)*(1+(alpha/kai0)*(3*(Ex(i,j,n+1,g))^2+(Ey(i,j,n+1,g))^2)+S(i,j,n+1));

that

            Ex(i,j,n+1,g)

exists -- in particular the n+1 is a problem.

[Junseob Kim]

I put Ex(i,j,n+1,1) instead of Ex(i,j,n,1). But there's still error.

[Junseob Kim]

Thanks you btw!!

[Walter Roberson]

You have the same issue for Ey except worse since you do not assign to Ey inside the loop and so are not growing Ey as you go.

You possibly also have problems accessing S.