$$$\left\langle \frac{657559773504431}{250000000000000}, - \frac{398521212616891}{250000000000000}, 1\right\rangle$$$的模

求$$$\mathbf{\vec{u}} = \left\langle \frac{657559773504431}{250000000000000}, - \frac{398521212616891}{250000000000000}, 1\right\rangle$$$的模（长度）。

向量的模由公式$$$\mathbf{\left\lvert\vec{u}\right\rvert} = \sqrt{\sum_{i=1}^{n} \left|{u_{i}}\right|^{2}}$$$给出。

各坐标绝对值的平方和为 $$$\left|{\frac{657559773504431}{250000000000000}}\right|^{2} + \left|{- \frac{398521212616891}{250000000000000}}\right|^{2} + \left|{1}\right|^{2} = \frac{326852006318417919663557569821}{31250000000000000000000000000}$$$。

因此，向量的模为 $$$\mathbf{\left\lvert\vec{u}\right\rvert} = \sqrt{\frac{326852006318417919663557569821}{31250000000000000000000000000}} = \frac{\sqrt{653704012636835839327115139642}}{250000000000000}$$$。

模长为 $$$\frac{\sqrt{653704012636835839327115139642}}{250000000000000}\approx 3.234078570812616$$$A。