$A$ Any Matrix
$B$ Basis Matrix
$C$ Cofactor Matrix
$D$ Diagonal Matrix
$E$ Elimination Matrix
$F$ Fourier Matrix
$H$ Hadamard Matrix
$I$ Identity Matrix
$J$ Jordan Matrix
$K$ Stiffness Matrix
$L$ Lower Triangular Matrix
$M$ Markov Matrix
$N$ Nullspace Matrix
$P$ Permutation Matrix
$P$ Projection Matrix
$O$ Orthogonal Matrix
$R$ Upper Triangular Matrix
$R$ Reduced Echelon Matrix
$S$ Symmetric Matrix
$T$ Linear Transformation
$U$ Upper Triangular Matrix
$U$ Left Singular Vectors
$V$ Right Singular Vectors
$X$ Eigenvector Matrix
$\Lambda$ Eigenvalue Matrix
$\Sigma$ Singular Value Matrix