Source code in the icon programming language

link matrix

procedure main ()
  m1 := [[1,2,3], [4,5,6]]
  m2 := [[1,2],[3,4],[5,6]]
  m3 := mult_matrix (m1, m2)
  write ("Multiply:")
  write_matrix ("", m1) # first argument is filename, or "" for stdout
  write ("by:")
  write_matrix ("", m2)
  write ("Result: ")
  write_matrix ("", m3)
end


procedure multiply_matrix (m1, m2)
  result := [] # to hold the final matrix
  every row1 := !m1 do { # loop through each row in the first matrix
    row := []
    every colIndex := 1 to *m1 do { # and each column index of the result
      value := 0
      every rowIndex := 1 to *m2 do { 
        value +:= row1[rowIndex] * m2[rowIndex][colIndex]
      }
      put (row, value) 
    }
    put (result, row) # add each row as it is complete
  }
  return result
end