Editing Square matrix (section)

==Main diagonal==
{{Main|Main diagonal}}
The entries <math>a_{ii}</math> ({{math|1=''i'' = 1, ..., ''n''}}) form the [[main diagonal]] of a square matrix. They lie on the imaginary line which runs from the top left corner to the bottom right corner of the matrix. For instance, the main diagonal of the 4×4 matrix above contains the elements {{math|1=''a''<sub>11</sub> = 9}}, {{math|1=''a''<sub>22</sub> = 11}}, {{math|1=''a''<sub>33</sub> = 4}}, {{math|1=''a''<sub>44</sub> = 10}}. 

The diagonal of a square matrix from the top right to the bottom left corner is called ''antidiagonal'' or ''counterdiagonal''.