From: William James <w_a_x_man@...>
Date: 2007-01-18T15:10:13+09:00
Subject: Re: Intensive computing: Ruby? Ruby/C? Pure C++?

William James wrote:
> Shot (Piotr Szotkowski) wrote:
> > Thanks a lot for taking the time to reply, Benjohn!
> >
> > benjohn@fysh.org:
> >
> > > I'd go with prototype in Ruby, probably.
> >
> > And then...? I hoped a bit for the dream solution of "actually, dear
> > professors, it works - if slow - for the scope of this thesis, and
> > further speed improvements can be achieved by replacing more parts
> > with C/C++ code". ;)
> >
> > > You could jump in to c++, and I think you may find useful Boost
> > > libraries for the work you're going (there is a graph librarby in
> > > there, I'm sure)
> >
> > Yeah, I heard good things about Boost, and also that wrapping one's mind
> > around C++ templating is a requirement these days. Of which, the latter
> > scares me (and I seem to know my limits quite well)...
> >
> > > but I honestly think you'll suffer if you're not a c++ Guru
> >
> > My thoughts exactly. The catch is my supervisor codes in C++ all his
> > life, while not having any idea about script languages, so he doesn't
> > really seem to easily buy mine 'I'll code both faster and be way more
> > happy with Ruby/OCaml, and the finished libraries will be more-or-less
> > universal anyway.'
> >
> > > After prototyping, a fourth way that I would strongly suggest in
> > > this case, is to considder a functional language if you need speed.
> >
> > The catch with going OCaml (where did today go? all these
> > easily-googlable tutorials and opinions were so nice to read...)
> > is that I'll have to learn yet another language (and, more importantly,
> > design paradigm).
>
> LuaJIT probably won't be as fast as OCaml, but I think Lua
> is easier for a Rubyist to learn.

Comparing Ruby to Lua and LuaJIT for intensively computing primes:

Ruby   245.763 seconds
Lua     10.685 seconds
LuaJIT   1.311 seconds

# the Ruby program
def prime(n)
  if n > 2 and n % 2 == 0
    return false
  end
  3.step( Math.sqrt(n).floor, 2){|i|
    if n % i == 0
      return false
    end
  }
  true
end

puts prime(2)
puts prime(4)
puts prime(7)
puts prime(25)
puts '----- the rest are primes'
time = Time.now
puts prime(1073676287)
puts prime(68718952447)
puts prime(87178291199)
puts prime(274877906899)
puts prime(549755813881)
puts prime(1099511627689)
puts prime(2199023255531)
puts prime(4398046511093)
puts prime(8796093022151)
puts prime(17592186044399)
puts prime(953467954114363)
puts Time.now - time


-- the Lua program
function prime(n)
  if n > 2 and n % 2 == 0 then
    return false
  end
  for i = 3, math.floor(math.sqrt(n)), 2 do
    if n % i == 0 then
      return false
    end
  end
  return true
end

print(prime(2))
print(prime(4))
print(prime(7))
print(prime(25))
print('----- the rest are primes')
time = os.clock()
print(prime(1073676287))
print(prime(68718952447))
print(prime(87178291199))
print(prime(274877906899))
print(prime(549755813881))
print(prime(1099511627689))
print(prime(2199023255531))
print(prime(4398046511093))
print(prime(8796093022151))
print(prime(17592186044399))
print(prime(953467954114363)) 
print(os.clock() - time)