Notes and urls.ipynb

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   "source": [
    "https://devblogs.nvidia.com/parallelforall/numbapro-high-performance-python-cuda-acceleration/\n",
    "\n",
    "https://devblogs.nvidia.com/parallelforall/even-easier-introduction-cuda/\n",
    "\n",
    "https://www.youtube.com/watch?v=zxzO2XmZJLw&feature=youtu.be\n",
    "\n",
    "https://gist.github.com/jedludlow/3919130\n",
    "\n"
   ]
  },
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   "metadata": {},
   "source": [
    "http://jakevdp.github.io/blog/2013/08/28/understanding-the-fft/"
   ]
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   "source": [
    "#http://jakevdp.github.io/blog/2013/08/28/understanding-the-fft/\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "def DFT_slow(x):\n",
    "    \"\"\"Compute the discrete Fourier Transform of the 1D array x\"\"\"\n",
    "    x = np.asarray(x, dtype=float)\n",
    "    N = x.shape[0]\n",
    "    n = np.arange(N)\n",
    "    k = n.reshape((N, 1))\n",
    "    M = np.exp(-2j * np.pi * k * n / N)\n",
    "    return np.dot(M, x)\n",
    "\n"
   ]
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       "True"
      ]
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     "execution_count": 2,
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   ],
   "source": [
    "x = np.random.random(1024)\n",
    "np.allclose(DFT_slow(x), np.fft.fft(x))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 512.32803240 +0.j        ,    3.96182092+10.15527021j,\n",
       "          1.21159181 -0.63214653j, ...,   -3.32708212 -6.89845514j,\n",
       "          1.21159181 +0.63214653j,    3.96182092-10.15527021j])"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "DFT_slow(x)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10 loops, best of 3: 192 ms per loop\n",
      "10000 loops, best of 3: 44 µs per loop\n"
     ]
    }
   ],
   "source": [
    "\n",
    "\n",
    "%timeit DFT_slow(x)\n",
    "%timeit np.fft.fft(x)\n",
    "\n"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
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    "collapsed": true
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