Names for Matrices

It is useful to have names for matrices. Usually a bold lower case letter is used for a column or a row matrix:

a = ( 1.2, -3.6 )
x = ( x1, x2, x3, x4 )
r = ( r0, r1 )T

It is conventional to use names from the start of the alphabet for column matrices whose elements we know (like a above), and to use names from the end of the alphabet for column matrices whose elements are variables.

Often the names of column matrix elements are subscripted versions of the name of the whole column matrix (like column matrix r and its elements r₀ and r₁).

Bold face is hard to do with pencil or chalk, so instead an arrow or a bar is placed over the name:

_    ->
x    x

x =  ( x1, x2 )
y =  ( 3.2, -8.6 )
x =  y