and checking that
condition (i) holds.
This approach has been taken by Crandall [28], Garner [34],
Schuppar [61] and Terras [67].
In estimating
, one can show that the quantities
are never very large, so that the size of
is essentially
determined by how large
can get.
The worst cases occur when
is a very close approximation to
,
i.e., when
is a very good rational approximation to
.
The best rational approximations to
are given by the convergents
of the continued fraction expansion of
.
Crandall [28]
uses general properties of continued fraction convergents to obtain the
following quantitative result.