\textstyle
but you can override this
by changing the \displaystyle
.
\begin{math} \begin{array}{clrr} % a+b+c & uv & x-y & 27 \\ x+y & w & +z & 363 \end{array} \end{math}produces
The rows are arranged so that their centres are aligned. You can align their tops or bottoms instead by using a further argument when you create the array.
\begin{array}{clrr}[t]would produce top-aligned lines, and
`[b]'
would produce
bottom-aligned ones. The Delimiters section of this document shows how
to bracket matrices.
TEX has a few maths facilities not mentioned in the LATEX book. The following TEX construction might be useful.
\begin{math} \bordermatrix{&a_1&a_2&...&a_n\cr b_1 & 1.2 & 3.3 & 5.1 & 2.8 \cr c_1 & 4.7 & 7.8 & 2.4 & 1.9 \cr ... & ... & ... & ... & ... \cr z_1 & 8.0 & 9.9 & 0.9 & 9.99 \cr} \end{math}