From: Gavin Kistner <gavin.kistner@...>
Date: 2006-10-26T06:50:24+09:00
Subject: Re: Premature Optimization

From: Gavin Kistner 
> However, I believe that's a pure-ruby implementation of matrices and
> vectors. A quick bit of Googling looks ike RNum[1] might be crazy fast
> and do what you need. I've never used it. I've also never used
> NArray[2], but it might do what you need.
> 
> [1] http://rnum.rubyforge.org/
> [2] http://narray.rubyforge.org/

So, I got NArray working on Windows with the One-Click Installer, and
yes, it's just a <sarcasm>*bit*</sarcasm> faster than the pure-ruby
Matrix:

require 'narray'
require 'matrix'
require 'benchmark'

ITERATIONS  = 4
NUM_VECTORS = 100
VECTOR_SIZE = 5000

Benchmark.bmbm{ |x|
  x.report( 'Create Matrix' ){
    ITERATIONS.times{
      @all = (1..NUM_VECTORS).map{
        Vector[ *(1..VECTOR_SIZE).map{ rand.round } ]
      }
    }
  }
  x.report( 'Add up Matrix' ){
    ITERATIONS.times{
      @all.inject{ |v1,v2| v1 + v2 }
    }
  }
  
  x.report( 'Create NArray' ){
    ITERATIONS.times{
      @all = (1..NUM_VECTORS).map{
        NVector[ *(1..VECTOR_SIZE).map{ rand.round } ]
      }
    }
  }
  x.report( 'Add up NArray' ){
    ITERATIONS.times{
      @all.inject{ |v1,v2| v1 + v2 }
    }
  }
}

Rehearsal -------------------------------------------------
Create Matrix   4.703000   0.016000   4.719000 (  4.719000)
Add up Matrix   8.297000   0.016000   8.313000 (  8.312000)
Create NArray   4.016000   0.000000   4.016000 (  4.032000)
Add up NArray   0.031000   0.000000   0.031000 (  0.031000)
--------------------------------------- total: 17.079000sec

                    user     system      total        real
Create Matrix   3.703000   0.000000   3.703000 (  3.704000)
Add up Matrix   8.250000   0.000000   8.250000 (  8.250000)
Create NArray   4.156000   0.000000   4.156000 (  4.156000)
Add up NArray   0.032000   0.000000   0.032000 (  0.031000)