RosettaCodeData/Task/Ackermann-function/Eiffel/ackermann-function.e

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note
description: "Example of Ackerman function"
synopsis: "[
The EIS link below (in Eiffel Studio) will launch in either an in-IDE browser or
and external browser (your choice). The protocol informs Eiffel Studio about what
program to use to open the `src' reference, which can be URI, PDF, or DOC. See
second EIS for more information.
]"
EIS: "name=Ackermann_function", "protocol=URI", "tag=rosetta_code",
"src=http://rosettacode.org/wiki/Ackermann_function"
EIS: "name=eis_protocols", "protocol=URI", "tag=eiffel_docs",
"src=https://docs.eiffel.com/book/eiffelstudio/protocols"
class
APPLICATION
create
make
feature {NONE} -- Initialization
make
do
print ("%N A(0,0):" + ackerman (0, 0).out)
print ("%N A(1,0):" + ackerman (1, 0).out)
print ("%N A(0,1):" + ackerman (0, 1).out)
print ("%N A(1,1):" + ackerman (1, 1).out)
print ("%N A(2,0):" + ackerman (2, 0).out)
print ("%N A(2,1):" + ackerman (2, 1).out)
print ("%N A(2,2):" + ackerman (2, 2).out)
print ("%N A(0,2):" + ackerman (0, 2).out)
print ("%N A(1,2):" + ackerman (1, 2).out)
print ("%N A(3,3):" + ackerman (3, 3).out)
print ("%N A(3,4):" + ackerman (3, 4).out)
end
feature -- Access
ackerman (m, n: NATURAL): NATURAL
do
if m = 0 then
Result := n + 1
elseif n = 0 then
Result := ackerman (m - 1, 1)
else
Result := ackerman (m - 1, ackerman (m, n - 1))
end
end
end