0. Array Logic Index   <<   >>


  (x>0) - (x<0)

            — Kenneth E. Iverson, A Programming Language, Wiley, 1962-05, §1.4


   x← 5 ¯2.7 0 6
 
   (x>0)-(x<0)
1 ¯1 0 1
  if x>0 then 1 else if x<0 then ¯1 else 0 
   x × (x>0)-(x<0)
5 2.7 0 6
if x≥0 then x else -x