Region Operators

       

The At, Of, and In operators are used to manipulate regions. The At operator on regions (at) is similar to the At operator on variables (@): it translates an index set by some specified direction. The Of operator (of) refers to a region that is adjacent to some specified region, and the In operator (in) refers to a region that is adjacent but inside of some specified region. These operators are defined more precisely below.

The At, Of and In operators can be used in combination to specify regions. The At operator is left-associative and binds most tightly, while the Of, and In operators are right-associative. For example, the

  R
  east of R
  east of east of R
  east of east of R at east
  east in (east of (east of (R at east)))

{\em linc: define these so that this is true, then show an example.}

• The Of Operator.
• The In Operator.
• The At Operator.