cython-fibonacci-comp.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# CPython"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "def fib1(n):\n",
    "    \"\"\"Get the n-th Fibonacci sequence number.\n",
    "    \n",
    "    Iterative implementation in CPython, variant 1.\n",
    "    \"\"\"\n",
    "    a, b = 0, 1\n",
    "    for _ in range(n):\n",
    "        a, b = b, a + b\n",
    "    return a\n",
    "\n",
    "\n",
    "def fib2(n):\n",
    "    \"\"\"Get the n-th Fibonacci sequence number.\n",
    "    \n",
    "    Iterative implementation in CPython, variant 2.\n",
    "    \"\"\"\n",
    "    a, b = 0, 1\n",
    "    while n > 0:\n",
    "        a, b = b, a + b\n",
    "        n -= 1\n",
    "    return a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5.28 µs ± 44.4 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "fib1(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "9 µs ± 250 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "fib2(100)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Cython\n",
    "\n",
    "Extra performance for free\n",
    "\n",
    "```bash\n",
    "$ pip install Cython\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "%load_ext Cython"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%%cython\n",
    "def fib3(int n):\n",
    "    \"\"\"Get the n-th Fibonacci sequence number.\n",
    "    \n",
    "    Iterative implementation in Cython, variant 1.\n",
    "    \"\"\"\n",
    "    if n <= 2:\n",
    "        return n\n",
    "    cdef unsigned long long a = 0\n",
    "    cdef unsigned long long b = 1\n",
    "    for _ in range(n):\n",
    "        a, b = b, a + b\n",
    "    return a\n",
    "\n",
    "\n",
    "def fib4(int n):\n",
    "    \"\"\"Get the n-th Fibonacci sequence number.\n",
    "    \n",
    "    Iterative implementation in Cython, variant 2.\n",
    "    \"\"\"\n",
    "    if n <= 2:\n",
    "        return n\n",
    "    cdef unsigned long long a = 0\n",
    "    cdef unsigned long long b = 1\n",
    "    while n > 0:\n",
    "        a, b = b, a + b\n",
    "        n -= 1\n",
    "    return a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "151 ns ± 1.33 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "fib3(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "143 ns ± 1.76 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "fib4(100)"
   ]
  }
 ],
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