Matrix from triple loop

I am trying to simplify the code from following loop:

for i = 1:10
    for j = 11:20
        RS_1(:,i) = signal(:,i) - signal(:,j);
    end
    for j = 21:30
        RS_2(:,i) = signal(:,i) - signal(:,j);
    end
    for j = 31:40
        RS_3(:,i) = signal(:,i) - signal(:,j);
        end
    for j = 41:50
        RS_4(:,i) = signal(:,i) - signal(:,j);
    end
    RS = [RS_1 RS_2 RS_3 RS_4];
end

With this one:

for i = 1:10
    for j = 11:50
        for k = 1:40
            RS(:,k) = signal(:,i) - signal(:,j);
        end
    end
end

I am wondering why do I get different matrix RS?

Answer 1

[Massimo Zanetti]

It doesn't work because your are using the RS_n matrices in your second code. This is a simplification of the first code:

RS_1(:,1:10) = signal(:,1:10) - signal(:,11:20);
RS_2(:,1:10) = signal(:,1:10) - signal(:,21:30);
RS_3(:,1:10) = signal(:,1:10) - signal(:,31:40);
RS_4(:,1:10) = signal(:,1:10) - signal(:,41:50);
RS = [RS_1 RS_2 RS_3 RS_4];

[cniv_we]

Hi thanks for the answer. Is it possible to loop this code? I tried this one:

for i = 1:10
    RS_1(:,i) = signal(:,i) - signal(:,10+i);
    RS_2(:,i) = signal(:,i) - signal(:,20+i);
    RS_3(:,i) = signal(:,i) - signal(:,30+i);
    RS_4(:,i) = signal(:,i) - signal(:,40+i);
    RS = [RS_1 RS_2 RS_3 RS_4];
end

But if possible I would like to loop 10+i, 20+i, ... as well so that I don't need to use RS_1, RS_2, etc. The dimension of matrix RS is 1000 rows x 40 columns.

[Massimo Zanetti]

Ah ok! simple like this:

for i=[11,21,31,41]
   RS(:,i-10:i-1) = signal(:,1:10)-signal(:,k:k+9);
end

That's it.

[cniv_we]

Thanks!