### 12.17.4 The harmonic conjugate: harmonic_conjugate

The harmonic_conjugate command takes as arguments three collinear points, three concurrent lines or three parallel lines.

harmonic_conjugate returns and draws the harmonic conjugate of the arguments.
Input:

harmonic_conjugate(0,2,3/2)

Output:

Input:

affix(harmonic_conjugate(0,2,3/2))

Output:

3

Input:

harmonic_conjugate(line(0,1+i),line(0,3+i),line(0,i))

Output: