定义了上三角等次对角线矩阵和上三角交错次对角线矩阵；
This paper defined up-triangle equal minor diagonal matrix and up-triangle stagger minor diagonal matrix.
把一张正方形的纸沿着对角线折成三角形，然后再对折一次。
Fold a piece of squared paper along the diagonal into a triangle, and fold into another triangle.
该干的“2”，并不去了第一次，然后再以正确的，但随即开始起飞，在对角线方向。
The stem of the "2" does not go up first and then to the right, but immediately starts-off in a diagonal direction.
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