Univariate Continued Fraction solver |
The family of methods based on continued fraction expansion proceed as follows:
Algorithm solve_continued_fraction(f,
Compute an integer lower
Shift
Compute the number
if
Split the polynomial
Apply reccursively the algorithm on
)
on the interval
.
where
is a
univariate polynomial expressed in the monomial basis
and
is an homography such that
and and
.
bound
of the positive roots of
;
by
:
;
of sign
changes of the coefficients of
;
then output the
corresponding isolation interval and stop; if
stop also;
in
whose positive roots correspond to
the roots of
in
,
whose positive
roots correspond to the roots of
in
.
and
.
where
and
are consecutive continued fraction
approximations of a root
of
and such that all roots of
of
is in one of these intervals.
Such a solver computes the first terms of the continued fraction expansion of the roots of a univariate polynomial. Two variants are also available, depending wether we want to isolate or approximate the real roots.