Interval Notation Calculator

Type an inequality and this returns it in interval notation, in set-builder form and as a number line description, with a note on why each bracket is the shape it is. It reads three-part forms with a bound on each side, pieces joined with and or or, not-equal, and all real numbers, and it takes the reverse direction too, turning an interval such as (-infinity, 3] U (7, infinity) back into an inequality. A third mode does set arithmetic on two intervals: union, intersection, A minus B and the complement of A. It works on one variable against plain numbers, so it converts notation rather than solving an inequality with an unknown on both sides.