subdiagonal

About 0.01 uses per million words.

Meaning

1. adjective Said of an entry of a square matrix: that it lies anywhere in the lower triangular area below the main diagonal of the matrix.
2. noun The diagonal of a matrix that lies directly below and to the left of the main diagonal.

Similar words

bidiagonal pentadiagonal tridiagonal offdiagonal unitriangular diagonalized nonbidiagonal nondefective diagonalisable subrecursive

Often followed by

elements element entries of and are is matrix