fannkuch-redux Julia program
source code
# The Computer Language Benchmarks Game
# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
# contributed by Jarret Revels and Alex Arslan
# based on the Javascript program
function perf_fannkuch(n)
p = Vector{Int32}(undef, n)
for i = 1:n
p[i] = i
end
q = copy(p)
s = copy(p)
sign = 1; maxflips = sum = 0
while true
q0 = p[1]
if q0 != 1
for i = 2:n
q[i] = p[i]
end
flips = 1
while true
qq = q[q0] #??
if qq == 1
sum += sign*flips
flips > maxflips && (maxflips = flips)
break
end
q[q0] = q0
if q0 >= 4
i = 2; j = q0-1
while true
t = q[i]
q[i] = q[j]
q[j] = t
i += 1
j -= 1
i >= j && break
end
end
q0 = qq
flips += 1
end
end
#permute
if sign == 1
t = p[2]
p[2] = p[1]
p[1] = t
sign = -1
else
t = p[2]
p[2] = p[3]
p[3] = t
sign = 1
for i = 3:n
sx = s[i]
if sx != 1
s[i] = sx-1
break
end
i == n && return [sum,maxflips]
s[i] = i
t = p[1]
for j = 1:i
p[j] = p[j+1]
end
p[i+1] = t
end
end
end
end
n = parse(Int,ARGS[1])
pf = perf_fannkuch(n)
println(pf[1])
println("Pfannkuchen(", n, ") = ", pf[2])
notes, command-line, and program output
NOTES:
64-bit Ubuntu quad core
julia version 1.11.0
Thu, 10 Oct 2024 00:43:45 GMT
MAKE:
printenv JULIA_NUM_THREADS
4
0.09s to complete and log all make actions
COMMAND LINE:
/opt/src/julia-1.11.0/bin/julia -O3 --cpu-target=ivybridge --math-mode=ieee -- fannkuchredux.julia 12
PROGRAM OUTPUT:
3968050
Pfannkuchen(12) = 65