derived relational algebra operators 关系代数的派生算子
Many science-related English words starting with the letters al—including algebra, alkaline, and algorithm—are derived from Arabic, in which the prefix al just means “the.”
很多与科学有关的英文单词开头字母都是al-如algebra（代数）、alkaline（碱）、和 algorithm（公式），事实上这来自于阿拉伯语，而阿拉伯语中的“al”是个没有任何意义的冠词，就像英语中的“the”一样。
The derived relational algebra operators are widely used in the relational database query languages.
关系代数的派生算子在关系数据库查询语言中得到了广泛应用。
The coordinate transformation matrix based on the direction cosine parameters from the object coordinate system to the world coordinate system is derived by vector algebra.
利用矢量代数的方法，推导出以方向余弦为参量的物坐标系到世界坐标系的坐标变换矩阵；利用矩阵求逆的方法，推导出世界坐标系到物坐标系的坐标变换矩阵。
应用推荐