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Bipolar cylindrical coordinates are a three-dimensional orthogonal coordinate system that results from projecting the two-dimensional bipolar coordinate system in the perpendicular -direction. The two lines of foci and of the projected Apollonian circles are generally taken to be defined by and , respectively, (and by ) in the Cartesian coordinate system. The term "bipolar" is often used to describe other curves having two singular points (foci), such as ellipses, hyperbolas, and Cassini ovals. However, the term ''bipolar coordinates'' is never used to describe coordinates associated with those curves, e.g., elliptic coordinates. ==Basic definition== The most common definition of bipolar cylindrical coordinates is : : : where the coordinate of a point equals the angle and the coordinate equals the natural logarithm of the ratio of the distances and to the focal lines : (Recall that the focal lines and are located at and , respectively.) Surfaces of constant correspond to cylinders of different radii : that all pass through the focal lines and are not concentric. The surfaces of constant are non-intersecting cylinders of different radii : that surround the focal lines but again are not concentric. The focal lines and all these cylinders are parallel to the -axis (the direction of projection). In the plane, the centers of the constant- and constant- cylinders lie on the and axes, respectively. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Bipolar cylindrical coordinates」の詳細全文を読む スポンサード リンク
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