bench/shootout/partialsums.ruby

   1 # ----------------------------------------------------------------------
   2 # The Great Computer Language Shootout
   3 # http://shootout.alioth.debian.org/
   4 #
   5 # Based on D language implementation by Dave Fladebo
   6 #
   7 # Contributed by Anthony Borla
   8 # ----------------------------------------------------------------------
   9
  10 n = (ARGV.shift || 1).to_i
  11
  12 alt = 1.0 ; s0 = s1 = s2 = s3 = s4 = s5 = s6 = s7 = s8 = 0.0
  13
  14 1.upto(n) do |d|
  15   d = d.to_f ; d2 = d * d ; d3 = d2 * d ; ds = Math.sin(d) ; dc = Math.cos(d)
  16
  17   s0 += (2.0 / 3.0) ** (d - 1.0)
  18   s1 += 1.0 / Math.sqrt(d)
  19   s2 += 1.0 / (d * (d + 1.0))
  20   s3 += 1.0 / (d3 * ds * ds)
  21   s4 += 1.0 / (d3 * dc * dc)
  22   s5 += 1.0 / d
  23   s6 += 1.0 / d2
  24   s7 += alt / d
  25   s8 += alt / (2.0 * d - 1.0)
  26
  27   alt = -alt
  28 end
  29
  30 printf("%.9f\t(2/3)^k\n", s0)
  31 printf("%.9f\tk^-0.5\n", s1)
  32 printf("%.9f\t1/k(k+1)\n", s2)
  33 printf("%.9f\tFlint Hills\n", s3)
  34 printf("%.9f\tCookson Hills\n", s4)
  35 printf("%.9f\tHarmonic\n", s5)
  36 printf("%.9f\tRiemann Zeta\n", s6)
  37 printf("%.9f\tAlternating Harmonic\n", s7)
  38 printf("%.9f\tGregory\n", s8)
  39