Ackermann function: Difference between revisions
Add improved Seed7 implementation
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(Add improved Seed7 implementation) |
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=={{header|Seed7}}==
===Basic version===
<syntaxhighlight lang="seed7">const func integer: ackermann (in integer: m, in integer: n) is func
result
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end func;</syntaxhighlight>
Original source: [http://seed7.sourceforge.net/algorith/math.htm#ackermann]
===Improved version===
<syntaxhighlight lang="seed7">$ include "seed7_05.s7i";
include "bigint.s7i";
const func bigInteger: ackermann (in bigInteger: m, in bigInteger: n) is func
result
var bigInteger: ackermann is 0_;
begin
case m of
when {0_}: ackermann := succ(n);
when {1_}: ackermann := n + 2_;
when {2_}: ackermann := 3_ + 2_ * n;
when {3_}: ackermann := 5_ + 8_ * pred(2_ ** ord(n));
otherwise:
if n = 0_ then
ackermann := ackermann(pred(m), 1_);
else
ackermann := ackermann(pred(m), ackermann(m, pred(n)));
end if;
end case;
end func;
const proc: main is func
local
var bigInteger: m is 0_;
var bigInteger: n is 0_;
var string: stri is "";
begin
for m range 0_ to 3_ do
for n range 0_ to 9_ do
writeln("A(" <& m <& ", " <& n <& ") = " <& ackermann(m, n));
end for;
end for;
writeln("A(4, 0) = " <& ackermann(4_, 0_));
writeln("A(4, 1) = " <& ackermann(4_, 1_));
stri := str(ackermann(4_, 2_));
writeln("A(4, 2) = (" <& length(stri) <& " digits)");
writeln(stri[1 len 80]);
writeln("...");
writeln(stri[length(stri) - 79 ..]);
end func;</syntaxhighlight>
Original source: [https://seed7.sourceforge.net/algorith/math.htm#bigInteger_ackermann]
{{out}}
<pre>
A(0, 0) = 1
A(0, 1) = 2
A(0, 2) = 3
A(0, 3) = 4
A(0, 4) = 5
A(0, 5) = 6
A(0, 6) = 7
A(0, 7) = 8
A(0, 8) = 9
A(0, 9) = 10
A(1, 0) = 2
A(1, 1) = 3
A(1, 2) = 4
A(1, 3) = 5
A(1, 4) = 6
A(1, 5) = 7
A(1, 6) = 8
A(1, 7) = 9
A(1, 8) = 10
A(1, 9) = 11
A(2, 0) = 3
A(2, 1) = 5
A(2, 2) = 7
A(2, 3) = 9
A(2, 4) = 11
A(2, 5) = 13
A(2, 6) = 15
A(2, 7) = 17
A(2, 8) = 19
A(2, 9) = 21
A(3, 0) = 5
A(3, 1) = 13
A(3, 2) = 29
A(3, 3) = 61
A(3, 4) = 125
A(3, 5) = 253
A(3, 6) = 509
A(3, 7) = 1021
A(3, 8) = 2045
A(3, 9) = 4093
A(4, 0) = 13
A(4, 1) = 65533
A(4, 2) = (19729 digits)
20035299304068464649790723515602557504478254755697514192650169737108940595563114
...
84717124577965048175856395072895337539755822087777506072339445587895905719156733
</pre>
=={{header|SETL}}==
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