The subdiagonal of a square matrix is the set of elements directly under the elements comprising the diagonal.
For example, in the following matrix, the diagonal elements are denoted 
and the subdiagonals are denoted 
,
![[d_1 a_(12) a_(13) ... a_(1n); s_1 d_2 a_(23) ... a_(2n); a_(31) s_2 d_3 ... a_(3n); | ... ... ... ...; a_(n1) a_(n2) a_(n3) ... d_n].](/images/equations/Subdiagonal/NumberedEquation1.svg) |
Subdiagonal
See also
Diagonal, Jordan Block, Superdiagonal, Tridiagonal MatrixExplore with Wolfram|Alpha
References
Faddeeva, V. N. Computational Methods of Linear Algebra. New York: Dover, p. 50, 1958.Referenced on Wolfram|Alpha
SubdiagonalCite this as:
Weisstein, Eric W. "Subdiagonal." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Subdiagonal.html