#author("2025-08-18T04:26:29+00:00","default:iseki","iseki") #author("2025-08-18T07:22:31+00:00","default:iseki","iseki") * Latex ** [[MathJax]] in Pukiwiki - $\vec{e1}$, $\vec{e2}$ - $A$ = $\begin{pmatrix} e1_x & e2_x \\ e1_y & e2_y \end{pmatrix}$ - $g_{ij}$ = $A^T A$ - $R = \begin{pmatrix} cosθ & -sinθ \\ sinθ & cosθ \end{pmatrix}$ - $A' = R A$ - $x' = A'^{-1} A x = A^{-1} R^{-1} A x$ - $x' = A^T R^{-1} A^{-T} x = (A^{-1} R A)^T x$ - $A = \begin{pmatrix} 1 & \frac{1}{\sqrt{2}} \\ 0 & \frac{1}{\sqrt{2}} \end{pmatrix}$ - $A^T = \begin{pmatrix} 1 & 0 \\ \frac{1}{\sqrt{2}} & \frac{1}{\sqrt{2}} \end{pmatrix}$ - $A^{-1} = \begin{pmatrix} 1 & -1 \\ 0 & \sqrt{2} \end{pmatrix}$ - $g_{ij} = A^T A = \begin{pmatrix} 1 & \frac{1}{\sqrt{2}} \\ \frac{1}{\sqrt{2}} & 1 \end{pmatrix}$