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