What is wrong with my code?

Hi. I am trying to write a function that takes two inputs (N and n) and return a n by n array at the top right corner of N. So far i have:

function M = top_right(N,n)
  M = N(1:n, 1:n);

Answer 1

[Star Strider]

I’m not exactly certain what you want to do.

See if this works for you:

N = 6;                                      % Argument
n = 3;                                      % Argument
M = zeros(N);                               % Create ‘M’
M(1:n, N-n+1:N) = 1                         % Set Top Right Corner To ‘1’

M =

M =

       0     0     0     1     1     1
       0     0     0     1     1     1
       0     0     0     1     1     1
       0     0     0     0     0     0
       0     0     0     0     0     0
       0     0     0     0     0     0

[Alexandra Huff]

I think that it what I want however, im trying for a more general code, not something as specific as that.

[Star Strider]

Another approach:

N = 6;                                      % Argument
n = 3;                                      % Argument
M = randi(99,N);                            % Create ‘M’
M(1:n, N-n+1:N) = rand(n)                   % Set Top Right Corner To ‘rand’

             79           68           70        0.119      0.34039      0.75127
             95           76            4      0.49836      0.58527       0.2551
             65           74           28      0.95974      0.22381      0.50596
              4           39            5            4           49           68
             85           65           10           44           45           65
             93           17           82           38           64           17

[Alexandra Huff]

The first way is what I want but I am trying to figure out how to do it without defining specifically what N and n is. Does that clarify what I am looking for better? So, I am trying to take two inputs N and n, where N's dimension is always greater than or equal to n. Then the function returns a n by n square array at the top right corner of N.

[Star Strider]

I don’t see any way to do what you want without specifically defining ‘N’ and ‘n’ unless you do it randomly:

N = randi(8);                               % Argument
n = randi(N-2);                             % Argument
M = zeros(N);                               % Create ‘M’
M(1:n, N-n+1:N) = 1                         % Set Top Right Corner To ‘1’

I’m keeping the matrices small for convenience. You can also define ‘n’ as:

n = randi(N-randi(N-1));

That way, you don’t have to define anything specifically, since all the parameters are random integers.

Answer 2

[Azzi Abdelmalek]

idx=sub2ind(size(N),1:n, 1:n)
M=N(idx)

Answer 3

[Walter Roberson]

M = N(1:n, end-n+1:end);