矩阵的级数：
定义：
\[{e^{tA}} = I + \frac{{tA}}{{1!}} + \frac{{{t^2}{A^2}}}{{2!}} + ... + \frac{{{t^k}{A^k}}}{{k!}} + ...\]
\[\sin (tA) = tA - \frac{{{t^3}{A^3}}}{{3!}} + ... + {( - 1)^k}\frac{{{t^{2k + 1}}{A^{2k + 1}}}}{{(2k + 1)!}} + ...\]
\[\cos (tA) = I - \frac{{{t^2}{A^2}}}{{2!}} + ... + {( - 1)^k}\frac{{{t^{2k}}{A^{2k}}}}{{(2k)!}} + ...\]