gistfile1.rb

class Matrix
  def []=(i, j, x)
    @rows[i][j] = x
  end
end

module Enumerable
  def sum
    return self.inject(0){|acc,i|acc +i}
  end
  def mean
    return self.sum/self.length.to_f
  end
  def sample_variance
    avg=self.mean
    sum=self.inject(0){|acc,i|acc +(i-avg)**2}
    return(1/self.length.to_f*sum)
  end
  def stddev
    return Math.sqrt(self.sample_variance)
  end
end