matmul.nelua

require 'sequence'

local Matrix = @sequence(sequence(number))

local function matrix_transpose(a: Matrix, n: integer): Matrix
  local x: Matrix = {}
  for i=1,n do
    x[i] = {}
    for j=1,n do
      x[i][j] = a[j][i]
    end
  end
  return x
end

local function matrix_multiply(a: Matrix, b: Matrix, n: integer): Matrix
  local x: Matrix = {}
  local c = matrix_transpose(b, n)
  for i=1,n do
    x[i] = {}
    for j=1,n do
      local sum = 0.0
      for k=1,n do
        sum = sum + a[i][k] * c[j][k]
      end
      x[i][j] = sum
    end
  end
  return x
end

local function matrix_generate(n: integer): Matrix
  local a: Matrix, tmp = {}, 1.0 / n / n
  for i=1,n do
    a[i] = {}
    for j=1,n do
      a[i][j] = tmp * (i - j - 2) * (i + j - 2)
    end
  end
  return a
end

local n = 200
local a = matrix_generate(n)
local b = matrix_generate(n)
local res = matrix_multiply(a, b, n)
print(res[n//2+1][n//2+1])