矩阵

• In other words, the hermiticity of a matrix is invariant under unitary transformations .
  换言之，矩阵的厄密性在幺正变换下保持不变。
• Since i behaves like the number 1 in ordinary algebra it is called the identity matrix .
  由于工具有普通代数中数1的性质，称它为幺矩阵。