1\par 2\chapter{{\tt A2}: Real or complex 2-D array} 3\par 4The {\tt A2} object is one way to store and operate on and 5with a dense matrix. 6The matrix can contain either double precision real or complex 7entries. 8It is used as a lower level object for the {\tt DenseMtx} object, 9and during the $QR$ factorization to hold a staircase matrix. 10\par 11