MATLAB 数组索引和切片

Question

Im writing currently rewriting a Matlab script in C. When i get to the last few lines of the Matlab script a for loop is executed and it iterates through an array. Since i am trying to rewrite the program in C the slicing notation in the Matlab script is confusing me. I have attached the line of code that is troubling me below.

How would i write this line of code in a nested for loop indexing with i and j only, since you cant slice in c obviously. just for reference u = 1, Ubc is 2D array of size (NX+2, NY+2). Where NX = NY = 40.

Below is the line of code in Matlab i need to translate to for loop indexing.

Nx = 40;
Ny = 40;
u = 1;
Ubc = rand(Nx + 2, Ny + 2);
% First the i interfaces
F =   0.5*    u *( Ubc(2:Nx+2,2:Ny+1) + Ubc(1:Nx+1,2:Ny+1)) 
     - 0.5*abs(u)*( Ubc(2:Nx+2,2:Ny+1) - Ubc(1:Nx+1,2:Ny+1));

Answer 1

You can calculate the same in a loop as

Nx = 40;
Ny = 40;
u = 1;
Ubc = rand(Nx + 2, Ny + 2);
F = zeros(Nx + 1, Ny);
for z1 = 1 : Nx + 1
    for z2 = 1 : Ny
        F(z1, z2) =   0.5*    u *( Ubc(z1 + 1, z2 + 1) + Ubc(z1, z2 + 1)) 
                    - 0.5*abs(u)*( Ubc(z1 + 1, z2 + 1) - Ubc(z1, z2 + 1));
    end
end

You shouldn't use i and j as loop index in Matlab. Both are the imaginary unit.