## 2 Methods
\begin{array}{c}\overline{\mathbf{p}}_{1}\\ \overline{\mathbf{p}}_{2}\end{array} \right]\text{,} \tag{19}\]  
where:  
\[\ddot{\overline{\mathbf{q}}}_{1}=\left[\ddot{\overline{q}}_{ji}\right]\text{, }\dot{\overline{\mathbf{q}}}_{1}=\left[\dot{\overline{q}}_{ji}\right]\text{, }\overline{\mathbf{q}}=\left[\overline{q}_{ji}\right]\text{, }\overline{\mathbf{p}}=\left[\overline{p}_{ji}\right]\text{,} \tag{20}\]\[\bar{\mathbf{\bar{q}}}_{2}=\left[ \begin{array}{c}\bar{q}_{1}^{l}\\ \bar{q}_{2}^{l}\\ \vdots\\ \bar{q}_{K}^{t}\\ \vdots\\ \bar{q}_{N_{k}}^{t}\end{array} \right],\bar{\mathbf{\bar{q}}}_{2}=\left[ \begin{array}{c}\dot{q}_{1}^{t}\\ \dot{q}_{2}^{t}\\ \vdots\\ \vdots\\ \dot{q}_{N_{k}}^{t}\end{array} \right],\mathbf{\bar{q}}_{2}=\left[ \begin{array} []{c}q_{1}^{t}\\ q_{2}^{t}\\ \vdots\\ \vdots\\ q_{N_{k}}^{t}\end{array} \right],\mathbf{\bar{p}}_{2}=\left[ \begin{array}{ c}0\\ 0\\ \vdots\\ 0\\ \vdots\\ 0\end{array} \right]. \tag{21}\]  
Similarly, the blocks associated with the discussed degrees of freedom shall also be separated from the matrix \(\mathbf{\overline{M}},\mathbf{\overline{C}},\mathbf{\overline{K}}\):  
\[\mathbf{\overline{M}}=\left[ \begin{array}{cc}\mathbf{\overline{M}}_{11}& \mathbf{\overline{M}}_{12}\\ \mathbf{\overline{M}}_{21}&\mathbf{\overline{M}}_{22}\end{array} \right], \mathbf{\overline{C}}=\left[ \begin{array}{cc}\mathbf{\overline{C}}_{11}& \mathbf{\overline{C}}_{12}\\ \mathbf{\overline{C}}_{21}&\mathbf{\overline{C}}_{22}\end{array} \right], \mathbf{\overline{K}}=\left[ \begin{array}{cc}\mathbf{\overline{K}}_{11}& \mathbf{\overline{K}}_{12}\\ \mathbf{\overline{K}}_{21}&\mathbf{\overline{K}}_{22}\end{array} \right]. \tag{22}\]  
The size of blocks \(\mathbf{\overline{M}}_{11}\), \(\mathbf{\overline{C}}_{11}\), \(\mathbf{\overline{K}}_{11}\) is \(1\times 1\); \(\mathbf{\overline{M}}_{12}\), \(\mathbf{\overline{C}}_{12}\), \(\mathbf{\overline{K}}_{12}\) is \(1\times N_{k}\); \(\mathbf{\overline{M}}_{21}\), \(\mathbf{\overline{C}}_{21}\), \(\mathbf{\overline{K}}_{21}\) is \(N_{k}\times 1\); and of \(\mathbf{\overline{M}}_{22}\), \(\mathbf{\overline{C}}_{22}\), \(\mathbf{\overline{K}}_{22}\) is \(N_{k}\times N_{k}\). Below you can find the forms of individual blocks of matrices \(\mathbf{\overline{M}},\mathbf{\overline{C}},\mathbf{\overline{K}}\). \[\mathbf{\overline{M}}_{11}=\left[\mathbf{\overline{m}}_{ji}\right],\mathbf{ \ \overline{M}}_{22}=\left[ \begin{array}{ccccc}m_{1}^{t}&0&\cdots&0&\cdots&0\\ 0&m_{2}^{t}&\cdots&0&\cdots&0\\ \vdots&\vdots&\ddots&\vdots&\ddots&\vdots\\ 0&0&\cdots&m_{k}^{t}&\cdots&0\\ \vdots&\vdots&\ddots&\vdots&\ddots&\vdots\\ 0&0&\cdots&0&\cdots&m_{N_{k}}^{t}\end{array} \right], \tag{23}\]  
\[\mathbf{\overline{M}}_{12}=\mathbf{\overline{M}}_{21}^{T}=\left[ \begin{array}[ ]{ccccc}0&0&\cdots&0&\cdots&0\end{array} \right], \tag{24}\]  
\[\mathbf{\overline{C}}_{11}=\left[\bar{c}_{ji}+\sum_{k=1}^{N_{k}}\frac{\bar{a} _{ki}^{2}}{{\bar{a_{ji}}}^{2}}c_{k}^{t}\right],\mathbf{\ \overline{C}}_{22}=\left[ \begin{array}{ccccc}c_{1}^{t}&0&\cdots&0&\cdots&0 \\ 0&c_{2}^{t}&\cdots&0&\cdots&0\\ \vdots&\vdots&\ddots&\vdots&\ddots&\vdots\\ 0&0&\cdots&0&\cdots&c_{N_{k}}^{t}\end{array} \right], \tag{25}\]  
\[\mathbf{\overline{C}}_{12}=\mathbf{\overline{C}}^{T}_{21}=\left[ \begin{array}[ ]{ccccc}-\frac{\bar{a}_{ii}}{\bar{a}_{ji}}c_{1}^{t}&-\frac{\bar{a}_{ii}}{\bar{ a}_{ji}}c_{2}^{t}&\cdots&-\frac{\bar{a}_{ii}}{\bar{a}_{ji}}c_{2}^{t}&\cdots&-\frac{\bar{a}_{ N_{k}i}}{\bar{a}_{ji}}c_{N_{k}}^{t}\end{array} \right], \tag{26}\]  
\[\mathbf{\overline{K}}_{11}=\left[\bar{k}_{ji}+\sum_{k=1}^{N_{k}}\frac{\bar{a} _{ki}^{2}}{{\bar{a_{ji}}}^{2}}k_{k}^{t}\right],\mathbf{\ \overline{K}}_{22}=\left[ \begin{array}{ccccc}k_{1}^{t}&0&\cdots&0&\cdots&0 \\ 0&k_{2}^{t}&\cdots&0&\cdots&0\\ \vdots&\vdots&\ddots&\vdots&\ddots&\vdots\\ 0&0&\cdots&k_{k}^{t}&\cdots&0\\ \vdots&\vdots&\ddots&\vdots&\ddots&\vdots\\ 0&0&\cdots&0&\cdots&k_{N_{k}}^{t}\end{array} \right], \tag{27}\]  
\[\mathbf{\overline{K}}_{21}=\mathbf{\overline{K}}^{T}_{12}=\left[