Why do I get an error "Matrix dimensions must agree."

I write my code with "for loops" I get working code but when i try to vectorized it get an error "Matrix dimensions must agree". What do you suggest to solve it ?

dy = 0.010;
dx = 0.010;
Nx = 100;                     
Ny = 100;                     
STEPS = 500;
Hx = zeros(Nx,Ny);
Hy = zeros(Nx,Ny);
Ez = zeros(Nx,Ny);
for a = 1:STEPS
    Hx(1:Nx,1:Ny) = Hx(1:Nx,1:Ny);
    Hy(1:Nx,1:Ny) = Hy(1:Nx,1:Ny);
    Ez(1:Nx,1:Ny) =(Hy(1:Nx,1:Ny)-Hy(1:Nx-1:Ny))/dx-(Hx(1:Nx,1:Ny)-Hx(1:Nx,1:Ny-1))/dy;
end

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Dyuman Joshi]

Why are you using a for loop for a task that is not changing with iterations?

"Why do I get an error "Matrix dimensions must agree.""

Because you are trying to add a (Nx)x(Ny) matrix with (Nx-1)x(Ny) matrix, while defining Ez.

[Rertan Ertan]

This is just an small segment of the code, in reality values inside the loop changing for ever iterations. I stucked with Ez array

[Dyuman Joshi]

"This is just an small segment of the code, in reality values inside the loop changing for ever iterations."

Then share all the relevant code and specify what you are trying to do and what is the expected output.