If statement is not triggering correctly

function Mnew = exchangeRows(M,i,j)
if i <=0 && j <=0 || i > length( M(:,1)) && j > length( M(:,1)) || j <=0 && i > length( M(:,1)) || i <=0 && j > length( M(:,1))
    warning('Row i and j are not valid')
    
elseif i <=0 || i > length ( M(:,1) )
      warning('Row i is not valid')
    
elseif j <=0 || j > length ( M(:,1) )
      warning('Row j is not valid')

For some reason is the first if statement is triggered when My i>=0 ,BUT my j is not >=0 or larger than the length of the matrix.

the same happens when my j is greater than the length of the matrix, BUT my i is not >=0 or larger than the matrix.

First i wrote the statement like this:

      if i <=0 || i > length ( M(:,1) ) && j <=0 || j > length ( M(:,1) )

but this brought the same problem thats why i try the rewrite it, without luck unfortunatley :C.

it is really strange because for all the other inputs it works fine

Update ive changed all the lengths with size(M,1), but this does not resolve the problem

[Walter Roberson]

Do we know for sure that i and j are scalars?

Using length(M(:,1)) is not recommended. Use size(M,1) instead.

Answer 1

[Walter Roberson]

all([i,j] >= 1) && all([i,j] <= size(M,1))