{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "using FFTW"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "dct (generic function with 1 method)"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "function dct(f)\n",
    "  function a(u, N)\n",
    "    if u == 0\n",
    "      sqrt(1/N)\n",
    "    else\n",
    "      sqrt(2/N)\n",
    "    end\n",
    "  end\n",
    "\n",
    "  if ndims(f) == 1\n",
    "    N = length(f)\n",
    "    [a(u, N) * sum([x * cos(pi * u * (2i - 1)/ (2N)) for (i, x) in enumerate(f)]) for u=0:N - 1]\n",
    "  elseif ndims(f) == 2\n",
    "    N, M = size(f)\n",
    "    [a(u, N) * a(v, M) * sum([f[x+1, y+1] * cos(pi * u * (2x + 1)/ (2N)) * cos(pi * v * (2y + 1) / (2M)) for x=0:N-1, y=0:M-1]) for u=0:N - 1, v=0:M-1]\n",
    "  else\n",
    "    error(\"What the hell man?\")\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "8-element Array{Float64,1}:\n",
       " 12.727922061357857     \n",
       " -6.4423230227051365    \n",
       " -1.3322676295501878e-15\n",
       " -0.6734548009039396    \n",
       "  0.0                   \n",
       " -0.20090290373599107   \n",
       " -2.6645352591003757e-15\n",
       " -0.05070232275964859   "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "8-element Array{Float64,1}:\n",
       " 12.727922061357857   \n",
       " -6.442323022705137   \n",
       "  0.0                 \n",
       " -0.6734548009039407  \n",
       "  0.0                 \n",
       " -0.20090290373599654 \n",
       "  0.0                 \n",
       " -0.050702322759645924"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "8×8 Array{Float64,2}:\n",
       "  260.0          -18.2216       -3.51701e-14  …  -4.89869e-14  -0.143408   \n",
       " -145.773         -3.55271e-15  -1.77636e-15      3.01981e-14   1.02141e-14\n",
       "   -4.14504e-14    5.32907e-15   0.0              0.0           1.77636e-15\n",
       "  -15.2385        -3.55271e-15   3.55271e-15     -7.10543e-15   0.0        \n",
       "    1.6329e-14    -1.77636e-15   3.55271e-15     -8.88178e-16   9.76996e-15\n",
       "   -4.54591       -5.32907e-15   0.0          …   0.0           5.9952e-15 \n",
       "   -5.33831e-14    1.15463e-14  -6.21725e-15     -4.44089e-16  -1.33227e-15\n",
       "   -1.14726       -2.66454e-15  -4.44089e-15     -2.22045e-15   2.66454e-15"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "8×8 Array{Float64,2}:\n",
       "  260.0      -18.2216  0.0  -1.90482  0.0  -0.568239  0.0  -0.143408\n",
       " -145.773      0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "    0.0        0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "  -15.2385     0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "    0.0        0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "   -4.54591    0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "    0.0        0.0     0.0   0.0      0.0   0.0       0.0   0.0     \n",
       "   -1.14726    0.0     0.0   0.0      0.0   0.0       0.0   0.0     "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "display(dct(1:8))\n",
    "\n",
    "display(FFTW.dct(1:8))\n",
    "\n",
    "display(dct([(i-1)*8 + j for i=1:8, j=1:8]))\n",
    "\n",
    "display(FFTW.dct([(i-1)*8 + j for i=1:8,j=1:8]))\n"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Julia 1.2.0-DEV",
   "language": "julia",
   "name": "julia-1.2"
  },
  "language_info": {
   "file_extension": ".jl",
   "mimetype": "application/julia",
   "name": "julia",
   "version": "1.2.0"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}