Main diagonal

In linear algebra, the main diagonal (sometimes leading diagonal) of a square matrix is the diagonal which runs from the top left corner to the bottom right corner. For example, the following matrix has 1s down its main diagonal:

Failed to parse (Missing texvc executable; please see math/README to configure.): \begin{bmatrix} 1 & 0 & 0\\ 0 & 1 & 0\\ 0 & 0 & 1\end{bmatrix}

A square matrix like the above in which the entries outside the main diagonal are all zero is called a diagonal matrix. The sum of the entries on the main diagonal of a matrix is known as the trace of that matrix.

The other diagonal is called antidiagonal, counterdiagonal or minor diagonal.ast:Diagonal principal ca:Diagonal principal de:Diagonale (Lineare Algebra) es:Diagonal principal fr:Diagonale principale it:Diagonale principale he:אלכסון ראשי lmo:Diagunala principala nl:Hoofddiagonaal ja:主対角線 pl:Macierz#Podstawowe_poj.C4.99cia pt:Diagonal de uma matriz ru:Главная диагональ fi:Päälävistäjä uk:Головна діагональ