幂等矩阵

例句：

1. 1. In linear algebra, an identity matrix is a special type of matrix that has all elements equal to one.
   在线性代数中，单位矩阵是一种特殊类型的矩阵，其所有元素都等于1。
2. 2. The identity matrix is used in many applications, such as solving systems of linear equations.
   单位矩阵在许多应用中都有使用，例如解决线性方程组。
3. 3. The identity matrix is also known as the diagonal matrix or the square matrix.
   单位矩阵也被称为对角矩阵或方阵。