| 861 |
|
\varphi _{b_m h}^2 \circ \varphi _{a_m h}^1 \circ \varphi _{b_{m - |
| 862 |
|
1} h}^2 \circ \ldots \circ \varphi _{a_1 h}^1 . |
| 863 |
|
\end{equation} |
| 864 |
< |
Careful choice of coefficient $a_1 \ldot b_m$ will lead to higher |
| 864 |
> |
Careful choice of coefficient $a_1 \ldots b_m$ will lead to higher |
| 865 |
|
order method. Yoshida proposed an elegant way to compose higher |
| 866 |
|
order methods based on symmetric splitting\cite{Yoshida1990}. Given |
| 867 |
|
a symmetric second order base method $ \varphi _h^{(2)} $, a |
| 1657 |
|
\] |
| 1658 |
|
, we obtain |
| 1659 |
|
\begin{eqnarray*} |
| 1660 |
< |
m\ddot x & = & - \frac{{\partial W(x)}}{{\partial x}} - |
| 1660 |
> |
m\ddot x & = & - \frac{{\partial W(x)}}{{\partial x}} - |
| 1661 |
|
\sum\limits_{\alpha = 1}^N {\left\{ {\left( { - \frac{{g_\alpha ^2 |
| 1662 |
|
}}{{m_\alpha \omega _\alpha ^2 }}} \right)\int_0^t {\cos (\omega |
| 1663 |
< |
_\alpha t)\dot x(t - \tau )d\tau \\ |
| 1664 |
< |
& &\mbox{} - \left[ {g_\alpha x_\alpha (0) - \frac{{g_\alpha |
| 1665 |
< |
}}{{m_\alpha \omega _\alpha }}} \right]\cos (\omega _\alpha t) - |
| 1666 |
< |
\frac{{g_\alpha \dot x_\alpha (0)}}{{\omega |
| 1667 |
< |
_\alpha }}\sin (\omega _\alpha t)} } \right\}} \\ |
| 1668 |
< |
% |
| 1669 |
< |
& = & - \frac{{\partial W(x)}}{{\partial x}} - \int_0^t |
| 1663 |
> |
_\alpha t)\dot x(t - \tau )d\tau } } \right\}} \\ |
| 1664 |
> |
& & + \sum\limits_{\alpha = 1}^N {\left\{ {\left[ {g_\alpha |
| 1665 |
> |
x_\alpha (0) - \frac{{g_\alpha }}{{m_\alpha \omega _\alpha }}} |
| 1666 |
> |
\right]\cos (\omega _\alpha t) + \frac{{g_\alpha \dot x_\alpha |
| 1667 |
> |
(0)}}{{\omega _\alpha }}\sin (\omega _\alpha t)} \right\}} |
| 1668 |
> |
\end{eqnarray*} |
| 1669 |
> |
\begin{eqnarray*} |
| 1670 |
> |
m\ddot x & = & - \frac{{\partial W(x)}}{{\partial x}} - \int_0^t |
| 1671 |
|
{\sum\limits_{\alpha = 1}^N {\left( { - \frac{{g_\alpha ^2 |
| 1672 |
|
}}{{m_\alpha \omega _\alpha ^2 }}} \right)\cos (\omega _\alpha |
| 1673 |
< |
t)\dot x(t - \tau )d} \tau } + \sum\limits_{\alpha = 1}^N {\left\{ |
| 1674 |
< |
{\left[ {g_\alpha x_\alpha (0) \\ |
| 1675 |
< |
& & \mbox{} - \frac{{g_\alpha }}{{m_\alpha \omega _\alpha }}} |
| 1673 |
> |
t)\dot x(t - \tau )d} \tau } \\ |
| 1674 |
> |
& & + \sum\limits_{\alpha = 1}^N {\left\{ {\left[ {g_\alpha |
| 1675 |
> |
x_\alpha (0) - \frac{{g_\alpha }}{{m_\alpha \omega _\alpha }}} |
| 1676 |
|
\right]\cos (\omega _\alpha t) + \frac{{g_\alpha \dot x_\alpha |
| 1677 |
|
(0)}}{{\omega _\alpha }}\sin (\omega _\alpha t)} \right\}} |
| 1678 |
|
\end{eqnarray*} |
