6.6. `sline` functions
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## 6.6. `sline` functions #

### 6.6.1. Begin and end #

To get the beginning and the end of a line, pgSphere provides two functions:

`sl_beg(` | line`)`; |

`sline line`;

`sl_end(` | line`)`; |

`sline line`;

Example 6.11. Get the beginning of a line

    sql> SELECT sl_beg( sline '(10d, 90d, 270d, ZXZ ), 20d';

### 6.6.2. Create a meridian #

You can create a meridian as a line using the function

`meridian(` | lng`)`; |

`float8 lng`;

The function returns a line starting at a latitude of -90° and ending at a latitude of 90°. The line goes along the given longitude `lng` in radians.

Example 6.12. A meridian for longitude 20°

    sql> SELECT set_sphere_output('DEG');
     set_sphere_output
    -------------------
     SET DEG
    (1 row)

    sql> SELECT meridian (20.0 *pi() / 180.0 );
                 sline
    -------------------------------
     ( 270d, 90d, 20d, ZXZ ), 180d
    (1 row)

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