You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: bm_so_matrix.rb
    path of file: ./repos/jruby/bench/mri
    
    the code of the file until where you have to start completion: #!/usr/bin/ruby
# -*- mode: ruby -*-
# $Id: matrix-ruby.code,v 1.4 2004/11/13 07:42:14 bfulgham Exp $
# http://www.bagley.o
    
def mmult(rows, cols, m1, m2)
    m3 = Array.new(rows)
    (0 .. (rows - 1)).each do |bi|
        row = Array.new(cols, 0)
        (0 .. (cols - 1)).each do |j|
            val = 0
            (0 .. (cols - 1)).each do |k|
                val += m1.at(bi).at(k) * m2.at(k).at(j)
            end
            row[j] = val
        end
        m3[bi] = row
    end
    m3
end