The functions
and
are conjugate to each other if
for some function
called the conjugating function. If the sequence
is defined by
![]()
![]()
for some
and
for![]()
then the sequence
satisfies
for![]()
and
and
are called conjugate iteration sequences.
In practice the function
is usually found by substituting
and
into
and rearranging.
Since the sequence
is the image of the sequence
under the function
both sequences must have the same behaviour of convergence and continuity and if
is a fixed point of
then
is a fixed point of![]()
If the conjugating function is to be one to one and entire then it must be of the form![]()
![]()
Example: Show that the sequence
![]()
![]()
is conjugate to the sequence
with conjugating function![]()
Note first that
is one to one on
If
then
so
becomes
for![]()
This simplifies to![]()
![]()
so that
and
are conjugate functions and the sequences
and
are conjugate sequences.