为什么矩阵必须是方阵很重要？（2018）
这篇来自Math StackExchange的讨论（2018年）探讨了方阵在线性代数中的核心重要性。方阵之所以关键，是因为只有方阵才有行列式、特征值、迹和逆矩阵（可逆时），而这些性质在求解线性方程组、矩阵对角化、以及理解线性变换的缩放因子和旋转特性中不可或缺。此外，方阵是唯一可以进行矩阵乘幂和定义矩阵指数的矩阵类型，这使其在微分方程、马尔可夫链和许多其他数学与工程领域具有基础性作用。
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