In
linear algebra, the
main diagonal (sometimes
principal diagonal,
primary diagonal,
leading diagonal, or
major diagonal) of a matrix
is the collection of entries
where . The following three matrices have their main diagonals indicated by red 1's:
The
antidiagonal (sometimes
counterdiagonal,
secondary diagonal,
trailing diagonal or
minor diagonal) of a dimension
square matrix,
, is the collection of entries such that . That is, it runs from the top right corner to the bottom left corner:
See also