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第二部分§9.齐次坐标一維齐次点坐标.当欧氏直线規定了方向、原点及单位线段以后,即建立起一种坐标系,它可使有穷远点与实数之間建立一一对应,从而确立了欧氏直线上点的坐标的概念。当它引进无穷远点建立射影直线后,无穷远点即沒有坐标而必須另行規定于下: 定义。笛氏坐标为x的点的一維齐次坐标(x_1,x_2)系任意适合x_1:x_2=x之二数x_1,x_2其中x2≠0,而
Part II §9. Homogeneous Coordinates One-Dimensional Homogeneous Coordinates. When a Euclidean straight line specifies the direction, origin, and unit line segment, a coordinate system is established that allows the establishment of a point between the finite point and the real number. One-to-one correspondence, thus establishing the concept of coordinates on the Euclidean point. When it has created an injective straight line at infinity, there is no coordinate at infinity and it must be specified separately: Definition. The one-dimensional homogeneous coordinate (x_1, x_2) of the point with the decanter coordinate x is arbitrarily suitable for the x_1:x_2=x two-digit x_1,x_2 where x2≠0, and