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# This file is part of Mailfromd testsuite. -*- Autotest -*-
# Copyright (C) 2007-2025 Sergey Poznyakoff
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
AT_SETUP([Ackerman function])
AT_KEYWORDS([ack])
MFT_RUN(
[/*
* This test computes the value of Ackerman function ack(3,8), which
* requires 2785999 calls of ack(). Maximum recursion depth is 2047,
* which requires 8188 words on stack. Heap allocation for echo arguments
* requires extra 7 words. Extra 3 words are required for envfrom arguments.
*/
#pragma stacksize 8198
func ack(number a, number b)
returns number
do
if a = 0
return b+1
fi
if b = 0
return ack(a-1,1)
fi
return ack(a-1, ack(a,b-1))
done
func main(...)
returns number
do
echo "ack(3,8)=" . ack(3,8)
return 0
done
],
[],
[0],
[],
[ack(3,8)=2045
])
AT_CLEANUP
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