点积
点积概念又称数量积或内积。
两个向量u,v的点积是一个标量，用u · v表示。通用公式：|u||v|cos<u,v>。在三维空间中代数公式：uxvx + uyvy + uzvz。（该公式可以先由二维证明，再推广到多维。二维中的证明：利用点线距公式和勾股定理推出|u|*cos<u,v>的表达式，再根据定义化简即可。）
点积的值由以下三个值确定：
u的大小v的大小u,v夹角的余弦。在u,v非零的前提下，点积如果为负，则u,v形成的角大于90度；如果为零，那么u,v垂直；如果为正，那么u,v形成的角为锐角。
点积得到两个向量的夹角的cos值，通过它可以知道两个向量的相似性，利用点积可判断一个多边形是否面向摄像机还是背向摄像机
点积英语例句翻译1.FRACTAL STUDY ON LATERAL ACCRETION SHALE BED OF POINT BAR
点坝侧积泥层分形研究收藏指正
2.FAST CONVOLUTION ALGORITHMS FOR DFT OF SIZE N=2~t
N=2~t点DFT的快速卷积算法收藏指正
3.The AIRS cloud-cleared radiance spectrum is spectrally reduced to mimic all MODISinfrared spectral bands within the AIRS spectral range. These aggregated measurements, MODIS-like in spectral coverage but at the spatial resolution of AIRS, are expressed as brightness temperatures and are compared with MODIS clear sky brightness temperature observations within all successfully cloud-cleared AIRS footprints.
将 AIRS的晴空辐射强度用MODIS的光谱响应函数卷积到所有的MODIS红外通道上,然后对所有晴空订正成功的象素点,将卷积的晴空辐射亮温与 MODIS的实际观测晴空亮温进行比较,发现在大部分MODIS红外通道上卷积亮温与MODIS晴空观测亮温的偏差和标准偏差分别为0.25K和 0.5K。收藏指正
4.How much dollars is one Ad Point?
一个积点值多少美元？收藏指正
5.A study on the lateral accretion body type of the meandering river point bar reservoirs.
曲流河点坝储集层侧积体类型研究收藏指正
6.One grave-digger took a wide shovel and little by little emptied the grave;
一个掘墓人拿起一把巨大的铁铲，一点一点地清除墓穴里的积土；收藏指正
7.Ordinary Accumulation Point on Direct Product of Chains
链直积上的明聚点收藏指正
8.Carefully stripping away (or off) centuries of dirt, the scientists uncovered a valuable old wall painting.
一点一点地拂去数百年的积尘，科学家们将一幅珍贵的石壁画显露了出来。收藏指正
9.What is your policy regarding automated accumulation of Ad Points?
贵公司对自动累积的积点作何处理？收藏指正
10.The problem of strong-distinguishable fullcoloring at the adjacent vertex of Cartesian product Pn×Pm of the path was discussed. The strong-distinguishable full-chromaticity number of Cartesian Pn×Pm was given as χast(Pn×Pm)=5 n=2,m≥2 or m=n=36 min{n,m}≥3 and m+n≠6
讨论路的笛卡尔积的邻点可区别的全染色问题,给出路的笛卡尔积Pn×Pm的邻点强可区别的全色数为χast(Pn×Pm)=5 n=2,m≥2或m=n=36 min{n,m}≥3且m+n≠6收藏指正