Week1-Matrix

1) The main diagonal：主对角线

2) Matrices donot commute：矩阵不遵循交换律

3) associative law：结合律

4）banded matrix：a diagonal matrix but instead of just the main diagonal，but always in this backslash(反斜杠) type

(This is a slash: /. Because the top of it leans forward, it is sometimes called a “forward slash.”

This is a backslash: \. Notice the way it leans back, distinguishing it from the regular slash.)

5）the product of two diagonal matrices is a diagonal matrix, with elements given by the product of the diagonal elements.

6）the product of two upper triangular matrices is an upper triangular matrix, with the diagonal elements of the product given by the product of the diagonal elements.

7）transpose，转置

8）skew-symmetric matrix：Transpose( A ) = - A 斜对称矩阵