{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Exercise 9\n\nExercise 9 with matplotlib.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import numpy as np\nimport matplotlib.pyplot as plt\n\nplt.figure(figsize=(8, 5), dpi=80)\nplt.subplot(111)\n\nX = np.linspace(-np.pi, np.pi, 256, endpoint=True)\nC = np.cos(X)\nS = np.sin(X)\n\nplt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\", label=\"cosine\")\nplt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\", label=\"sine\")\n\nax = plt.gca()\nax.spines[\"right\"].set_color(\"none\")\nax.spines[\"top\"].set_color(\"none\")\nax.xaxis.set_ticks_position(\"bottom\")\nax.spines[\"bottom\"].set_position((\"data\", 0))\nax.yaxis.set_ticks_position(\"left\")\nax.spines[\"left\"].set_position((\"data\", 0))\n\nplt.xlim(X.min() * 1.1, X.max() * 1.1)\nplt.xticks(\n    [-np.pi, -np.pi / 2, 0, np.pi / 2, np.pi],\n    [r\"$-\\pi$\", r\"$-\\pi/2$\", r\"$0$\", r\"$+\\pi/2$\", r\"$+\\pi$\"],\n)\n\nplt.ylim(C.min() * 1.1, C.max() * 1.1)\nplt.yticks([-1, +1], [r\"$-1$\", r\"$+1$\"])\n\nt = 2 * np.pi / 3\nplt.plot([t, t], [0, np.cos(t)], color=\"blue\", linewidth=1.5, linestyle=\"--\")\nplt.scatter(\n    [\n        t,\n    ],\n    [\n        np.cos(t),\n    ],\n    50,\n    color=\"blue\",\n)\nplt.annotate(\n    r\"$sin(\\frac{2\\pi}{3})=\\frac{\\sqrt{3}}{2}$\",\n    xy=(t, np.sin(t)),\n    xycoords=\"data\",\n    xytext=(+10, +30),\n    textcoords=\"offset points\",\n    fontsize=16,\n    arrowprops={\"arrowstyle\": \"->\", \"connectionstyle\": \"arc3,rad=.2\"},\n)\n\nplt.plot([t, t], [0, np.sin(t)], color=\"red\", linewidth=1.5, linestyle=\"--\")\nplt.scatter(\n    [\n        t,\n    ],\n    [\n        np.sin(t),\n    ],\n    50,\n    color=\"red\",\n)\nplt.annotate(\n    r\"$cos(\\frac{2\\pi}{3})=-\\frac{1}{2}$\",\n    xy=(t, np.cos(t)),\n    xycoords=\"data\",\n    xytext=(-90, -50),\n    textcoords=\"offset points\",\n    fontsize=16,\n    arrowprops={\"arrowstyle\": \"->\", \"connectionstyle\": \"arc3,rad=.2\"},\n)\n\nplt.legend(loc=\"upper left\")\n\nplt.show()"
      ]
    }
  ],
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      "display_name": "Python 3",
      "language": "python",
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    "language_info": {
      "codemirror_mode": {
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      "file_extension": ".py",
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