Linear Algebra and Its Applications · Problem 1.4.7

Matrices and Gaussian Elimination — Gilbert Strang

Mathematics · matrix-notation-and-multiplication

Problem

Give 3 by 3 examples (not just the zero matrix) of (a) a diagonal matrix:

a_{ij} = 0

i \neq j

. (b) a symmetric matrix:

a_{ij} = a_{ji}

for all

i

and

j

. (c) an upper triangular matrix:

a_{ij} = 0

i > j

. (d) a skew-symmetric matrix:

a_{ij} = -a_{ji}

for all

i

and

j