From: Todd Benson <caduceass@...>
Date: 2007-10-29T08:05:21+09:00
Subject: Re: How do I define a dynamic Matrix or ....

On 10/28/07, Victor Reyes <victor.reyes@gmail.com> wrote:
> Hello Team,
>
> On my quest to learn Ruby, I implemented a known algorithm to solve an odd
> nXn magic square.
> I tested my code using a 3x3 and a 5x5 magic squares.
> The problem that I am having is that I hard-code the initialization matrix.
> In other words, if it is a 3x3 I define:
>
> mm = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
>
> For a 5 x 5 I define :
>
> mm = [[0,0,0, 0, 0], [0,0,0, 0, 0], [0,0,0, 0, 0],[0,0,0,0,0],[0,0,0,0,0]]
>
> I want to be able to solve any size odd magic square. To do so, I need to be
> able to define my matrix dynamically and on demand.
> Can anyone tell me how to do that?
>
> Attached is my current code. Please feel free to criticize it and make
> recommendations. My disclaimer: I am a Ruby apprentice.
>
> Thank you
>
> Victor
>
> #!/usr/local/bin/ruby -d -W0
>
> def mag(size)
>     r = 0                           # row
>     c = 0                          # column
>     index = 0                     # pointer
>
>    # mm = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
>     mm = [[0,0,0, 0, 0], [0,0,0, 0, 0], [0,0,0, 0,
> 0],[0,0,0,0,0],[0,0,0,0,0]]
>
>     maxLoop = size * size                           # Magic Square size
>
>     1.upto(maxLoop) do |n|
>
>       case
>           when n == 1
>               c = (size / 2).floor                      # Will keep the
> integer part, giving us the center in row 0
>               mm[c][r] = n                             # This is: mm[c][0]
>           when index >= size
>               index = 0
>               r = r + 1
>               mm[c][r] = n
>               puts " "
>           else
>               c = c + 1
>               if c >= size
>                 c = 0
>               end
>
>               r = r -1
>               if r < 0
>                 r = size - 1
>               end
>               mm[c][r] = n
>           end
>           index = index + 1
>
>       puts "[#{c}][#{r}] = #{mm[c][r]} "
>
>    end   # End upto
>
>     ##############
>     # Output the matrix    #
>     ##############
>     puts
>     0.upto(size -1) do |r|
>       0.upto(size -1) do |c|
>         print "#{mm[c][r]} "
>       end
>       puts " "
>     end
>
>  end # End method mag
>
>  # We start here
>
>  p1 = ARGV[0].to_i
>
>  mag( p1 )

irb> odd_matrix_number = 7
irb> my_matrix - Array.new(odd_matrix_number) {
Array.new(odd_matrix_number) {0} }

I'm not sure exactly what is your assignment, but it might be good to
create a MagicSquare object.

My half a cent.

Todd