3.5. Line #
A spherical line is part of a great circle (meridian) that has a beginning and an end and hence, a direction. Use cases are:
direct connection of two points
meteors on the sky sphere
To allow lines with a length larger than 180°, the input i syntax is a somewhat complex.
A general located line with a length
length is defined as a line starting at
position (0d,0d) and ending at position
(length,0d) transformed with an Euler
transformation euler. The input syntax
is :
( euler ), length
Note
For a simpler line input, use casting operators (Section 5.1) or constructor functions (Chapter 4).
If the length is larger than 360°, the line length is truncated to 360°.
The transformation
eulerwill always be converted to an Euler transformation using axesZ,X, andZ.
Example 3.8. A line input
A line starting at position (200d,+20d)
and ending at position (200d,-10d).
sql> SELECT sline '( -90d, -20d, 200d, XYZ ), 30d ';