Numerical Ruby

I was looking for something to run to try to put the current Ruby 1.9 through its paces. The first code I found was this

total = 0.0

1.0.step(2000.0,0.0001) do |x|

  result = (5.4*x**5 - 3.211*x**4 + 100.3*x**2 - 100 +
    20*Math.sin(x) - Math.log(x)) * 20*Math.exp(-x/100.3)
  total += result / 0.0001

end

puts total

Its heavy on the floating point that’s what I mostly use; ‘normal’ use is more likely integer math. Its a nonsensical calculation that I should rework as a real integration problem…

Timings (intel iMac)

imac:$ time ruby pure_ruby.rb
1.31784023450574e+24

real    1m43.283s
user    1m38.615s
sys     0m1.213s
imac:$ time /usr/local/ruby1.9/bin/ruby pure_ruby.rb
1.31784023450574e+24

real    1m1.352s
user    0m58.550s
sys     0m0.749s

Which is 1.7x faster. Not bad for no additional work. These numbers are very preliminary, and shouldn’t be mistaken for real benchmarks. I have a series of tests I did with pair correlation function calculations on a simulated liquid that I want to rerun and see how 1.9 holds up.