26.12.4 Coordinates of a point, vector or line in the plane
See Section 27.10.4 for coordinates in 3D
geometry.
The coordinates
finds the coordinates of a point or two points that determine a line.
-
coordinates takes
X, either a point, a sequence or list of points, or a line.
- coordinates(X) returns:
-
a list consisting of the abscissa and ordinate of X, if
X is a point or a vector, or a sequence or list of such lists,
if X is a sequence or list of points.
- a list of two points on the line X, in the order
determined by the direction of the line, if X is a line.
Examples
or:
| coordinates(point(1+2*i)) |
or:
| coordinates(vector(1+2*i)) |
| coordinates(point(1+2*i)-point(i)) |
or:
| coordinates(vector(i,1+2*i)) |
or:
| coordinates(vector(point(i),point(1+2*i))) |
or:
| coordinates(vector([0,1],[1,2])) |
or:
| d:=line(point(-1,1),point(1,2)) |
then:
| coordinates(line(y=x/2+3/2)) |
| coordinates(line(x-2*y+3=0)) |
or:
| coordinates(point(i),point(1+2*i)) |
Note that if the argument is a list of real numbers, it is
interpreted as a list of points on the real axis.