Decimal BASIC Open Source Project

Playing a little with the Ackermann function:

'===============================================
' The Ackermann Function
' ~~~~~~~~~~~~~~~~~~~~~~
' Function named after Wilhelm Ackermann (1926):
' ack(a,b,0) = a+b
' ack(a,0,n+1) = psi(a,n)
' ack(a,b+1,n+1) = ack(a,ack(a,b,n+1),n)
' R¢zsa P‚ter defined 1955 a simple two-argument Version,
' the Ackermann-P‚ter function:
' a(0,n) = n+1
' a(m+1,0) = a(m,1)
' a(m+1,n+1) = a(m,a(m+1,n))
' ~~~~~~~~~~~~~~~~~~~~~~
OPTION ARITHMETIC DECIMAL_HIGH
OPTION BASE 1
PRINT " Function Ackermann (M, N) :"
INPUT PROMPT "M": x
INPUT PROMPT "N": y
FOR I = 1 TO x ! This is M
FOR J = 1 TO y ! This is N
PRINT "Ackermann(" & STR$(I) & "," & STR$(J) & ")="; ackermann(I, J)
NEXT J
NEXT I
function ackermann(m, n)
if (m = 0) then
LET ackermann = (n + 1)
elseif (n = 0) then
LET ackermann = ackermann((m - 1), 1)
else
LET ackermann = ackermann((m - 1), ackermann(m, (n - 1)))
END if
end function
END
'===============================================
My program calculates until Ackermann (3,9).
Ackermann (3,10) doesn't work and also Ackermann(4,1)!
Is there a possibillity to improve this ?