Interoperable interactive geometry for Europe
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Families are not elements, but sets of elements used to provide for polymorphism. They are used as if they were elements in the constraints especifications in order to reduce the number of constraints; for example, instead of having three constraints such as

  1. point_intersection_of_two_lines(point, line, line)
  2. point_intersection_of_line_and_line_segment(point, line, line_segment)
  3. point_intersection_of_two_line_segments(point, line_segment, line_segment)
we define only one constraint that takes any kind of argument in the line_family:
  1. point_intersection_of_two_lines(point, line_family, line_family)

List of families:

  • line_family = {line, ray, line_segment, directed_line_segment}
  • circle family = {circle, arc}
  • conic_family = {circle, circle arc, conic, parabola, ellipse, hyperbola}
  • element_family = {all elements}