On Mon, Aug 4, 2008 at 10:24 PM, Marcio Braga <mbraga0001 / gmail.com> wrote:
>> http://www.ruby-lang.org/ja/man/html/Matrix.html#Matrix.23.5b.5d.3d
>> Harry
>
> The example of that page:
>
> m=Matrix[[11,12],[21,22]]
> m[1,1]=-1
>
> ... gives me the following error message:
>
> undefined method '[]=' for Matrix[[11, 12], [21, 22]]:Matrix
> (NoMethodError)

You have to open the class and define the method as in the example...

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

Todd