matrix_mod.rb

require 'matrix'

class Matrix

  alias old_minor minor

  def minor(*param)
    if param.size == 2 and param[0].kind_of?(Integer) and param[1].kind_of?(Integer)
      rows = []
      @rows.size.times do |i|
        next if i == param[0]
        rows << (@rows[i][0, param[1]] or []) + 
          (@rows[i][param[1] + 1, @rows.size - param[1] - 1] or [])
      end
      Matrix.rows(rows, false)
    else
      old_minor(param)
    end
  end

  def adjugate
    Matrix.Raise ErrDimensionMismatch unless square?

    rows = Array.new(@rows.size) { [] }

    rows.size.times do |row|
      rows.size.times do |col|
        rows[row][col] = (((row + col) % 2) == 0 ? 1 : -1) * minor(row, col).det
      end
    end

    Matrix.rows(rows, false).t
  end

  alias adj adjugate

end