def mda(width,height)
  a = Array.new(width)
  a.map! { Array.new(height) }
  return a
end

m_array = mda(10,10)

m_array[5][7] = "i10"
m_array[8][9] = 42

puts m_array[5][7]
"i10"

puts m_array[8][9]
42