定义什么叫做identity matrices:
The n x n identity matrix, denoted
, is a matrix with n rows and n columns. 矩阵里面的元素,从左上角到右下角都是1,剩余的部分都是0.
比如说:
任何一个n x n 矩阵跟identity matrices相乘,最后都是得到原来的矩阵。换句话说:
A
I = I
A = A.
比如说:
The identity matrix I plays a similar role to what the number 1 plays in the real number system. A 1 = 1 A = A.
现在定义什么是multiplicative inverses
两个实数的乘积是乘法恒等式,称为multiplicative inverses. 比如说,
2 = 1 和 2
= 1,那么
和2 就是multiplicative inverses.
事实上,all nonzero real numbers have multiplicative inverses.