Rachuan - when I run the code, the matrix nodos is modified. In fact, a seventh column is appended to the original 4x6 matrix. Look at the condition that when true, updates the matrix
if nodos(i,5)==0
nodos(i,7)=w+1
w=w+1
end
So if the fifth element of the ith row is zero, then you set the seventh element of the ith row to w+1. But since your matrix is 4x6, a seventh column of zeros is automatically added to the matrix with only nodos(i,7) equal to one. The code then increments w and proceeds to the next iteration of the loop. But the first line of the for loop body
So even though we have incremented w, we have reset it to zero. I suspect that you only want to initialize w to zero outside of the for loop. So you may want to revise your code as
nodos = [0 0 0 0 1 1; 48 0 0 0 1 1;84 0 0 0 1 1;48 36 -500 0 0 0]
Nnodos = 4;
w = 0;
for i=1:Nnodos
if nodos(i,5)==0
nodos(i,7)=w+1;
w=w+1;
end
end
Now decide what should happen when nodos(i,5)==0 0 do you want to add a new column, or update an existing one with nodos(i,??)=w+1;
