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List:       ruby-talk
Subject:    Matrix class in Ruby
From:       jasa <jasa () dalton ! inesc ! pt>
Date:       2002-02-28 15:18:39
[Download RAW message or body]

Hi,

Today I just played with the Matrix class (file matrix.rb) to solve
linear systems.
I have the Ruby 1.6.5 Windows distribution from PragProg (archive
'ruby165-2.exe').
I verified that the 'matrix.rb' file is the same in the
'ruby-1.6.6.tar.gz' distribution.
The header of this file goes in the end of this email.

I was surprised that the class has not the method '[]=', only has the
method '[]'.
So, I can get one value of the matrix, but I cannot set a value.
        ^^^^^^                                            ^^^^^^^^

A TRIVIAL (I'm just a modest Ruby user, not an hacker B-) .... )
addition to 'matrix.rb' put element 'setting' to work. I just created a
new method '[]=' as follows

#####   the  line in matrix.rb is about 280...

  #accessing                   #<<<< ALREADY EXISTS
  def [](i, j)
    @rows[i][j]
  end

  # setting                      #<<<<<  NEW METHOD...
  def []=(i, j, val)
    @rows[i][j] = val
  end

My only question is that if there is any reason, that I cannot see,
for the method '[]=' not being implemented before ???????
(could Keiju ISHITSUKA reply, please). Is there any danger in
setting an element in the matrix?

Thanks in advance for any reply.

Greetings

J. Augusto

-------------------------------------------------------------------------------

P.S.     The matrix class in the library has the following header (the
same as Ruby 1.6.6):

#!/usr/local/bin/ruby
#
#   matrix.rb -
#    $Release Version: 1.0$
#    $Revision: 1.11 $
#    $Date: 1999/10/06 11:01:53 $
#       Original Version from Smalltalk-80 version
#    on July 23, 1985 at 8:37:17 am
#    by Keiju ISHITSUKA
#
.........................



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