Data update

Task/Ackermann-function/REXX/ackermann-function.rexx

@@ -0,0 +1,83 @@
+-- 27 Oct 2025
+include Setting
+numeric digits 310000
+
+say 'ACKERMANN FUNCTION'
+say version
+say
+call Ackermann1
+call Ackermann2
+exit
+
+Ackermann1:
+procedure expose glob.
+say 'Using recursion...'
+do i=0 to 3
+   do j=0 to 10
+      say 'Ackermann('i','j')' '=' Acker1(i,j) Elaps('r')'s'
+   end
+end
+say
+return
+
+Acker1:
+procedure
+arg xx,yy
+select
+   when xx = 0 then
+      return yy+1
+   when yy = 0 then
+      return Acker1(xx-1,1)
+   otherwise
+      return Acker1(xx-1,Acker1(xx,yy-1))
+end
+
+Ackermann2:
+procedure expose glob.
+say 'Using closed formulas...'
+do i=0 to 3
+   do j=0 to 10
+      say 'Ackermann('i','j')' '=' Acker2(i,j) Elaps('r')'s'
+   end
+end
+say 'Ackermann(3,100) =' Acker2(3,100) Elaps('r')'s'
+say 'Ackermann(3,1000) has' Length(Acker2(3,1000)) 'digits' Elaps('r')'s'
+say 'Ackermann(3,10000) has' Length(Acker2(3,10000)) 'digits' Elaps('r')'s'
+say 'Ackermann(3,100000) has' Length(Acker2(3,100000)) 'digits' Elaps('r')'s'
+say 'Ackermann(3,1000000) has' Length(Acker2(3,1000000)) 'digits' Elaps('r')'s'
+say 'Ackermann(4,0) =' Acker2(4,0) Elaps('r')'s'
+say 'Ackermann(4,1) =' Acker2(4,1) Elaps('r')'s'
+say 'Ackermann(4,2) has' Length(Acker2(4,2)) 'digits' Elaps('r')'s'
+return
+
+Acker2:
+procedure
+arg xx,yy
+select
+   when xx=0 then
+      rr=yy+1
+   when xx=1 then
+      rr=yy+2
+   when xx=2 then
+      rr=yy+yy+3
+   when xx=3 then
+      rr=2**(yy+3)-3
+   when xx=4 then
+      select
+         when yy=0 then
+            rr=2**(2**2)-3
+         when yy=1 then
+            rr=2**(2**(2**2))-3
+         when yy=2 then
+            rr=2**(2**(2**(2**2)))-3
+         otherwise
+            rr=0
+      end
+   otherwise
+      rr=0
+end
+return rr
+
+include Abend
+-- Elaps
+include Timer