Imaginary unit.

  The variables i and j both initially have the value sqrt(-1)

  for use in forming complex quantities.  For example, the

  expressions 3+2i, 3+2*i, 3+2i, 3+2*j and 3+2*sqrt(-1).

  all have the same value.  However, both i and j may be 

  assigned other values, often in FOR227HPXR loops and as subscripts.



  See also J21KTHXR.