Import JJIO
Class Recursions
-- Name jmotil
-- Does show recursive examples

Function fact (num) ofType int is public
   Slot num ofType int
   Box  result ofType int
-- Does compute the factorial recursively
   If (num == 0) then
      Set result = 1
   Else
      Set result = num * fact (num - 1)
   EndIf
EndFunction fact

Function sqr (n) ofType int is public
   Slot n ofType int
   Box  result ofType int
-- Does compute the square recursively
   If (n == 0) then
      Set result = 0
   Else
      Set result = sqr (n-1) + n + n - 1
   EndIf
EndFunction sqr

Function fib (n) ofType int is public
   Slot n ofType int
   Box  result ofType int
-- Does compute fibonacci recursively
   If (n == 0) then
      Set result = 1
   ElseIf (n == 1) then
      Set result = 1
   Else
      Set result = fib(n - 1) + fib(n-2)
   EndIf
EndFunction fib

Function power (x,n) ofType real is public
   Slot x ofType real
   Slot n ofType int
   Box  result ofType real
-- Does compute the power recursively
   If (n == 0) then
      Set result = 1.0
   Else
      Set result = x * power (x, n-1)
   EndIf
EndFunction power

Function pow2 (x,n) ofType real is public
   Slot x ofType real
   Slot n ofType int
   Box  result ofType real
-- Does compute the power recursively
   If (n == 0) then
      Set result = 1.0
   ElseIf ( (n % 2) == 0) then -- odd n
      Set result = x * pow2 (x, n-1)
   Else -- even n
      Set result = pow2 (x, n/2) * 
                   pow2 (x, n/2)
   EndIf
EndFunction pow2

Routine doCurse (many, curse) is public
   Slot many  ofType  int
   Slot curse ofClass Str
-- Does repeat curse many times
   If (many > 0) then
      Output curse
      Call doCurse with (many-1, curse)
   EndIf
EndRoutine doCurse

Routine mainTest (none) is private
   Boxes i,j,k ofType int
-- Does test the recursive methods
Start
   Set i = 5
   Outputln fact (i)
   Outputln sqr  (i)
   Outputln fib  (i)
   Outputln power(2.0, i)
   Call doCurse with (i, "@#% ")
EndRoutine mainTest

EndClass Recursions