The general R-stage implicit Runge-Kutta method is defined by
![](Images/image001.png) |
(6.1) |
where
![](Images/image003.png)
with
![](Images/image005.png) |
(6.2) |
and
, ![](Images/image009.png) |
(6.3) |
The functions are no longer defined explicitly but by a set of implicit equations and thus making the derivation of such methods tedious. We shall consider here only the two-stage method obtained by setting in (6.1)-(6.3). Let us also recall the expansion for which is given by
![](Images/image019.png) |
(6.4) |
where, extending the notation of (3.18)
![](Images/image021.png)
![](Images/image023.png)
![](Images/image025.png) |