he reference, unless stated
otherwise, is
[Schewchuk]
.
The primary interest of this chapter is solving a linear equation of the
form


(Linear equation)

Most of the time
is symmetric positive definite or, at least, symmetric. We will be interested
in extension to more generic matrixes as well. The solution
is the equation (
Linear equation
) will be
approximated with some sequence
,
with a property
.
In such context we will be using the notations
and
(error and
residual)


(Error and residual)

Note
that


(Error and residual 2)

