13.6.3  The difference and sum of two points in the plane:+ -

Let A and B be two points in the plane, with affixes a₁ + i a₂ and b₁ + ib₂ respectively.
Input:

Then:

• The difference B−A returns the affix (b₁−a₁)+i(b₂−a₂), which represents the vector AB.
  Input:
  vector(A,B); vector(point(0),point(B-A))
  Output:
  
• The sum B+A returns the affix (b₁+a₁)+i(b₂+a₂). If D:= point(B+A), then BD = OA.
  Input:

  D:= point(B + A);

  segment(B,D); segment(point(0),A)

  Output:
  

Note that −A is the point symmetrical to A with respect to the origin.

The sum of three points A + B + C can be viewed as the translate of C by the vector A + B. So if A or B contains parameters, you should write this as C + (A + B) or evalc(A + B) + C.