Question

I have a 2d matrix, i want to traverse all elements in this matrix something like this:

a = 
0  1  2
5  4  3
6  7  8

for i = 1 : 81
    a(i) = ....
....

now, for example when i use a(2), i received “5”, but i want a(2) give me “1”. in the other word, i want use linear indexing with rows traversal instead of columns.

Answer 1

To traverse an array down rows try something like this. Here a has col_count columns and row_count rows

for j = 1:col_count
   for i=1:row_count
       a(i,j)       %# display element at row i, column j
   end
end

This will print out your elements in turn starting with first column, printing element of each row in that column in row order. This is repeated for each column.

edit: If you must use a single index then just use your current single index notation, but act on the transpose of your matrix:

 b = a.'
 for i = 1:size
     b(i)     
 end