27.10.4 Coordinates of a point, vector or line in space
See Section 26.12.4 for coordinates in 2D
geometry.
The coordinates
command takes finds the coordinates of a point.
-
coordinates takes
P, which can be a point (or a sequence or list of points), a
vector, or a line.
- If P is a point, then coordinates(P) returns a list
consisting of the abscissa, ordinate and cote. If P is a list or
sequence of points, then the command returns a list or sequence of
such lists.
- If P is a vector, for example from A to B, then
coordinates(P) returns a list of the coordinates of B−A.
- If P is a line, then coordinates(P) returns a
list of two points on the line, in the order determined by the
direction of the line.
Examples
coordinates(point(1,2,3)) |
coordinates(point(0,1,2),point(1,2,4)) |
Note that if the argument is a list of real numbers, it is
interpreted as a list of points on the real axis of the plane.
coordinates(vector(point(1,2,3),point(2,4,7))) |
coordinates(line(point(-1,1,0),point(1,2,3))) |
|
| ⎡
⎣ | ⎡
⎣ | −1,1,0 | ⎤
⎦ | , | ⎡
⎣ | 1,2,3 | ⎤
⎦ | ⎤
⎦ |
| | | | | | | | | | |
|
coordinates(line(x-2*y+3=0, 6*x+3*y-5*z+3=0)) |
|
| ⎡
⎣ | ⎡
⎣ | −1,1,0 | ⎤
⎦ | , | ⎡
⎣ | 9,6,15 | ⎤
⎦ | ⎤
⎦ |
| | | | | | | | | | |
|