[Shootout-list] Faster Ruby Fibonacci Benchmark

[Jabari Zakiya]

require 'benchmark'
include Benchmark

def fib1(n) if n<2 then n else fib1(n-1)+ fib1(n-2) end end

def fib2(n) n<2 ? n : fib2(n-1)+ fib2(n-2) end

def fib3(n) if n>1 then fib1(n-1)+ fib1(n-2) else n end end

def fib4(n) n>1 ? fib4(n-1)+ fib4(n-2) : n end=20

n=3D20
bmbm(12) do |x|
  x.report("fib1") { n.times { fib1(25) } }
  x.report("fib2") { n.times { fib2(25) } }
  x.report("fib3") { n.times { fib3(25) } }
  x.report("fib4") { n.times { fib4(25) } }
end

=3Dbegin

The following times were generated from the above benchmark.
600Mhz Athlon K-7, 640MB, Mandrake 10.1 Official, Ruby 1.8.2

Rehearsal -----------------------------------------------
fib1         11.850000   0.000000  11.850000 ( 12.099299)
fib2         11.950000   0.000000  11.950000 ( 12.144117)
fib3         11.830000   0.000000  11.830000 ( 11.973985)
fib4         11.410000   0.000000  11.410000 ( 11.568537)
------------------------------------- total: 47.040000sec

                  user     system      total        real
fib1         11.810000   0.000000  11.810000 ( 11.982514)
fib2         11.960000   0.000000  11.960000 ( 12.103553)
fib3         11.830000   0.000000  11.830000 ( 12.022400)
fib4         11.410000   0.000000  11.410000 ( 11.553338)

fib4 is fastest, which is faster than Shootout version fib1.
Note: These versions produce the correct fibonacci sequence
for all index values n (n=3D0,1,2,3,4,5...)

Jabari Zakiya
=3Dend



--=20
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