# Checking if circles are in a bundle: is_harmonic_circle_bundle

### 13.16.17 Checking if circles are in a bundle: is_harmonic_circle_bundle

The is_harmonic_circle_bundle command determines how circles are related.

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

#### Example.

Input:

is_harmonic_circle_bundle([circle(0,i),circle(4,i),circle(0,1/2)])

Output:

1