Checking if lines are in a bundle: is_harmonic_line_bundle

### 13.16.16 Checking if lines are in a bundle: is_harmonic_line_bundle

The is_harmonic_line_bundle command determines how lines are related.

- is_harmonic_line_bundle takes one argument:
  L, a list or sequence of lines.
- is_harmonic_line_bundle(L) returns:
  - 1 if the lines pass through a common point
  - 2 if the lines are parallel
  - 3 if the lines are the same
  - 0 otherwise

#### Example

Input:

is_harmonic_line_bundle([line(0,1+i),line(0,2+i),line(0,3+i),line(0,1)])

Output:

1