Since the iteration matrix M defined defined by the canonical eigenvalue problems from Section 1.2 is symmetric, M has a complete set of orthogonal eigenvectors which can be be denoted by

Then,

where, for i>0,
is the
Chebyshev iterate
generated by Equation (11),
is the initial iterate, and
is an eigenvalue of M
corresponding to the eigenvector
.
Consider the inner product of the
and
iterates, i.e.,
Equation (18) is equivalent to the continuous integral
when
is defined to be the following discrete non-negative
distribution ([10])

By choosing l=0 in Equation (19) and
,
it follows that

Note that the final orthogonal polynomial
has a zero at each
eigenvalue i.e.,
.
Hence, at each step of the Chebyshev semi-iterative method, we can
extract the
modified moment

The extraction of moments from iterates can be accelerated by using the recurrence relations for the Chebyshev polynomials defined in Equation (9). Specifically, one can show (see [22]) that
Note that the polynomial
in Equation (15)
associated with the modified moments
and
satisfies

where the coefficients
of the polynomials
in Equation (16) are given by