rref.rb

class Matrix < Array
    def initialize(filename)
        # read file
        f = File.open(filename) or die("no such file or reading error.")
        @row, @col = f.readline.split(' ').map(&:to_i)
        f.each_line { |line|
            line = line.split(' ').map(&:to_r)
            self.push(line)
        }
    end

    def to_rref!()
        lead = 0
        @row.times { |r|
            return if lead == @col
            i = r
            while self[i][lead] == 0
                if (i+=1) == @row
                    i = r
                    return if (lead+=1) == @col
                end
            end
            self[r], self[i] = self[i], self[r]
            v = self[r][lead]
            self[r].map! {|n| n / v}
            for k in 0...@row
                if not k == r
                    v = self[k][lead]
                    self[k].map!.with_index { |n, c| n-v*self[r][c]}
                end
            end
            lead += 1
        }
    end

    def show()
        self.each { |row|
            row.each { |item| print "#{item.to_i} " }
            puts
        }
    end
end
mtx = Matrix.new(ARGV[0])
mtx.to_rref!
mtx.show