在曲面上做一些网格，你会看到一个网上的每一小块儿，都是小的平行四边形，我们要弄清楚它的面积和法向量是什么。

You will get some sort of mesh grid on your surface and you will look at a little parallelogram that is an elementary piece of that mesh and figure out what is its area and normal vector.

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如果你要画一个网格(例如缩略图)先画出所有的平行线作为一连串的长线来保持线的长度和角度都一致。

If you're drawing a grid (of thumbnails, for instance), draw all parallel lines first as a series of long dashes to help keep line lengths and angles consistent.

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本文提出平面上拉普拉斯算子在一类平行六边形网格上的成对4点差分格式。

In this paper we propose so-called coupled 4-point difference schemes for the Laplacian operator over a class of parallel hexagon partitions of the plane.

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