diff --git a/tools_numpy.ipynb b/tools_numpy.ipynb
index 580815c..2cc6191 100644
--- a/tools_numpy.ipynb
+++ b/tools_numpy.ipynb
@@ -15,10 +15,10 @@
    "source": [
     "<table align=\"left\">\n",
     "  <td>\n",
-    "    <a href=\"https://colab.research.google.com/github/ageron/handson-ml2/blob/master/tools_numpy.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a>\n",
+    "    <a href=\"https://colab.research.google.com/github/ageron/handson-ml3/blob/main/tools_numpy.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://kaggle.com/kernels/welcome?src=https://github.com/ageron/handson-ml2/blob/master/tools_numpy.ipynb\"><img src=\"https://kaggle.com/static/images/open-in-kaggle.svg\" /></a>\n",
+    "    <a target=\"_blank\" href=\"https://kaggle.com/kernels/welcome?src=https://github.com/ageron/handson-ml3/blob/main/tools_numpy.ipynb\"><img src=\"https://kaggle.com/static/images/open-in-kaggle.svg\" /></a>\n",
     "  </td>\n",
     "</table>"
    ]
@@ -377,13 +377,12 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "%matplotlib inline\n",
     "import matplotlib.pyplot as plt"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 23,
+   "execution_count": 22,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -447,7 +446,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 25,
+   "execution_count": 24,
    "metadata": {
     "scrolled": true
    },
@@ -459,7 +458,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 26,
+   "execution_count": 25,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -476,7 +475,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 27,
+   "execution_count": 26,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -496,7 +495,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 28,
+   "execution_count": 27,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -514,7 +513,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 29,
+   "execution_count": 28,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -531,7 +530,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 30,
+   "execution_count": 29,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -561,7 +560,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 31,
+   "execution_count": 30,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -572,7 +571,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 32,
+   "execution_count": 31,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -583,7 +582,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 33,
+   "execution_count": 32,
    "metadata": {
     "scrolled": true
    },
@@ -604,7 +603,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 34,
+   "execution_count": 33,
    "metadata": {
     "scrolled": true
    },
@@ -624,7 +623,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 35,
+   "execution_count": 34,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -641,7 +640,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 36,
+   "execution_count": 35,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -658,7 +657,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 37,
+   "execution_count": 36,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -675,7 +674,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 38,
+   "execution_count": 37,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -718,7 +717,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 39,
+   "execution_count": 38,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -735,7 +734,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 40,
+   "execution_count": 39,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -752,7 +751,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 41,
+   "execution_count": 40,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -769,7 +768,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 42,
+   "execution_count": 41,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -785,7 +784,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 43,
+   "execution_count": 42,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -801,7 +800,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 44,
+   "execution_count": 43,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -818,7 +817,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 45,
+   "execution_count": 44,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -846,7 +845,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 46,
+   "execution_count": 45,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -856,7 +855,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 47,
+   "execution_count": 46,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -873,7 +872,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 48,
+   "execution_count": 47,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -897,7 +896,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 49,
+   "execution_count": 48,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -914,7 +913,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 50,
+   "execution_count": 49,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -930,7 +929,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 51,
+   "execution_count": 50,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -956,7 +955,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 52,
+   "execution_count": 51,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -976,7 +975,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 53,
+   "execution_count": 52,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -993,7 +992,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 54,
+   "execution_count": 53,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1003,7 +1002,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 55,
+   "execution_count": 54,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1012,7 +1011,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 56,
+   "execution_count": 55,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1028,7 +1027,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 57,
+   "execution_count": 56,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1037,7 +1036,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 58,
+   "execution_count": 57,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1054,7 +1053,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 59,
+   "execution_count": 58,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1071,7 +1070,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 60,
+   "execution_count": 59,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1082,6 +1081,13 @@
     "    print(func(a))"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The two warnings are due to the fact that `sqrt()` and `log()` are undefined for negative numbers, which is why there is a `np.nan` value in the first cell of the output of these two functions."
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -1092,7 +1098,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 61,
+   "execution_count": 60,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1103,7 +1109,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 62,
+   "execution_count": 61,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1112,7 +1118,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 63,
+   "execution_count": 62,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1121,7 +1127,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 64,
+   "execution_count": 63,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1139,7 +1145,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 65,
+   "execution_count": 64,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1149,7 +1155,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 66,
+   "execution_count": 65,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1158,7 +1164,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 67,
+   "execution_count": 66,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1167,7 +1173,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 68,
+   "execution_count": 67,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1176,7 +1182,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 69,
+   "execution_count": 68,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1185,7 +1191,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 70,
+   "execution_count": 69,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1201,7 +1207,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 71,
+   "execution_count": 70,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1218,7 +1224,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 72,
+   "execution_count": 71,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1236,7 +1242,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 73,
+   "execution_count": 72,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1253,7 +1259,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 74,
+   "execution_count": 73,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1272,7 +1278,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 75,
+   "execution_count": 74,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1291,7 +1297,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 76,
+   "execution_count": 75,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1302,7 +1308,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 77,
+   "execution_count": 76,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1319,7 +1325,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 78,
+   "execution_count": 77,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1330,7 +1336,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 79,
+   "execution_count": 78,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1348,7 +1354,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 80,
+   "execution_count": 79,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1358,7 +1364,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 81,
+   "execution_count": 80,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1367,7 +1373,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 82,
+   "execution_count": 81,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1376,7 +1382,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 83,
+   "execution_count": 82,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1392,7 +1398,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 84,
+   "execution_count": 83,
    "metadata": {
     "scrolled": true
    },
@@ -1403,7 +1409,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 85,
+   "execution_count": 84,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1427,7 +1433,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 86,
+   "execution_count": 85,
    "metadata": {
     "scrolled": true
    },
@@ -1438,7 +1444,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 87,
+   "execution_count": 86,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1454,7 +1460,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 88,
+   "execution_count": 87,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1471,7 +1477,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 89,
+   "execution_count": 88,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1481,7 +1487,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 90,
+   "execution_count": 89,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1490,7 +1496,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 91,
+   "execution_count": 90,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1506,7 +1512,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 92,
+   "execution_count": 91,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1523,7 +1529,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 93,
+   "execution_count": 92,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1532,7 +1538,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 94,
+   "execution_count": 93,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1541,7 +1547,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 95,
+   "execution_count": 94,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1550,7 +1556,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 96,
+   "execution_count": 95,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1567,7 +1573,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 97,
+   "execution_count": 96,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1577,7 +1583,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 98,
+   "execution_count": 97,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1587,7 +1593,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 99,
+   "execution_count": 98,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1605,7 +1611,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 100,
+   "execution_count": 99,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1614,7 +1620,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 101,
+   "execution_count": 100,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1630,7 +1636,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 102,
+   "execution_count": 101,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1647,7 +1653,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 103,
+   "execution_count": 102,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1657,7 +1663,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 104,
+   "execution_count": 103,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1668,7 +1674,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 105,
+   "execution_count": 104,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1686,7 +1692,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 106,
+   "execution_count": 105,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1704,7 +1710,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 107,
+   "execution_count": 106,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1714,7 +1720,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 108,
+   "execution_count": 107,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1724,7 +1730,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 109,
+   "execution_count": 108,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1742,7 +1748,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 110,
+   "execution_count": 109,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1752,7 +1758,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 111,
+   "execution_count": 110,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1771,7 +1777,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 112,
+   "execution_count": 111,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1781,7 +1787,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 113,
+   "execution_count": 112,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1797,7 +1803,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 114,
+   "execution_count": 113,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1817,7 +1823,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 115,
+   "execution_count": 114,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1827,7 +1833,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 116,
+   "execution_count": 115,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1851,7 +1857,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 117,
+   "execution_count": 116,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1861,7 +1867,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 118,
+   "execution_count": 117,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1880,7 +1886,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 119,
+   "execution_count": 118,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1897,7 +1903,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 120,
+   "execution_count": 119,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1907,7 +1913,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 121,
+   "execution_count": 120,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1916,7 +1922,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 122,
+   "execution_count": 121,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1932,7 +1938,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 123,
+   "execution_count": 122,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1942,7 +1948,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 124,
+   "execution_count": 123,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1961,7 +1967,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 125,
+   "execution_count": 124,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1978,7 +1984,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 126,
+   "execution_count": 125,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -1988,7 +1994,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 127,
+   "execution_count": 126,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2004,7 +2010,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 128,
+   "execution_count": 127,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2014,7 +2020,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 129,
+   "execution_count": 128,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2030,7 +2036,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 130,
+   "execution_count": 129,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2040,7 +2046,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 131,
+   "execution_count": 130,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2060,7 +2066,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 132,
+   "execution_count": 131,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2070,7 +2076,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 133,
+   "execution_count": 132,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2086,7 +2092,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 134,
+   "execution_count": 133,
    "metadata": {
     "scrolled": true
    },
@@ -2098,7 +2104,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 135,
+   "execution_count": 134,
    "metadata": {
     "scrolled": true
    },
@@ -2116,7 +2122,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 136,
+   "execution_count": 135,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2126,7 +2132,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 137,
+   "execution_count": 136,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2143,7 +2149,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 138,
+   "execution_count": 137,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2153,7 +2159,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 139,
+   "execution_count": 138,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2163,7 +2169,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 140,
+   "execution_count": 139,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2187,7 +2193,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 141,
+   "execution_count": 140,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2199,7 +2205,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 142,
+   "execution_count": 141,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2215,7 +2221,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 143,
+   "execution_count": 142,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2232,7 +2238,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 144,
+   "execution_count": 143,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2248,7 +2254,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 145,
+   "execution_count": 144,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2265,7 +2271,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 146,
+   "execution_count": 145,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2275,7 +2281,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 147,
+   "execution_count": 146,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2284,7 +2290,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 148,
+   "execution_count": 147,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2301,7 +2307,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 149,
+   "execution_count": 148,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2318,7 +2324,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 150,
+   "execution_count": 149,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2328,7 +2334,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 151,
+   "execution_count": 150,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2337,7 +2343,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 152,
+   "execution_count": 151,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2354,7 +2360,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 153,
+   "execution_count": 152,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2364,7 +2370,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 154,
+   "execution_count": 153,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2374,7 +2380,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 155,
+   "execution_count": 154,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2390,7 +2396,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 156,
+   "execution_count": 155,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2401,7 +2407,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 157,
+   "execution_count": 156,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2410,7 +2416,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 158,
+   "execution_count": 157,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2426,7 +2432,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 159,
+   "execution_count": 158,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2435,11 +2441,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 160,
+   "execution_count": 159,
    "metadata": {},
    "outputs": [],
    "source": [
-    "np.trace(m3)  # equivalent to np.diag(m3).sum()"
+    "m3.trace()  # equivalent to np.diag(m3).sum()"
    ]
   },
   {
@@ -2461,7 +2467,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 161,
+   "execution_count": 160,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2480,7 +2486,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 162,
+   "execution_count": 161,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2496,7 +2502,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 163,
+   "execution_count": 162,
    "metadata": {
     "scrolled": true
    },
@@ -2517,15 +2523,16 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 164,
+   "execution_count": 163,
    "metadata": {},
    "outputs": [],
    "source": [
     "import math\n",
+    "\n",
     "data = np.empty((768, 1024))\n",
     "for y in range(768):\n",
     "    for x in range(1024):\n",
-    "        data[y, x] = math.sin(x*y/40.5)  # BAD! Very inefficient."
+    "        data[y, x] = math.sin(x * y / 40.5)  # BAD! Very inefficient."
    ]
   },
   {
@@ -2537,7 +2544,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 165,
+   "execution_count": 164,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2549,7 +2556,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 166,
+   "execution_count": 165,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2567,11 +2574,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 167,
+   "execution_count": 166,
    "metadata": {},
    "outputs": [],
    "source": [
-    "data = np.sin(X*Y/40.5)"
+    "data = np.sin(X * Y / 40.5)"
    ]
   },
   {
@@ -2583,14 +2590,15 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 168,
+   "execution_count": 167,
    "metadata": {},
    "outputs": [],
    "source": [
     "import matplotlib.pyplot as plt\n",
     "import matplotlib.cm as cm\n",
+    "\n",
     "fig = plt.figure(1, figsize=(7, 6))\n",
-    "plt.imshow(data, cmap=cm.hot, interpolation=\"bicubic\")\n",
+    "plt.imshow(data, cmap=\"hot\")\n",
     "plt.show()"
    ]
   },
@@ -2607,7 +2615,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 169,
+   "execution_count": 168,
    "metadata": {
     "scrolled": true
    },
@@ -2619,7 +2627,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 170,
+   "execution_count": 169,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2635,7 +2643,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 171,
+   "execution_count": 170,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2654,7 +2662,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 172,
+   "execution_count": 171,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2672,7 +2680,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 173,
+   "execution_count": 172,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2688,7 +2696,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 174,
+   "execution_count": 173,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2705,13 +2713,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 175,
-   "metadata": {
-    "collapsed": true,
-    "jupyter": {
-     "outputs_hidden": true
-    }
-   },
+   "execution_count": 174,
+   "metadata": {},
    "outputs": [],
    "source": [
     "np.savetxt(\"my_array.csv\", a, delimiter=\",\")"
@@ -2726,7 +2729,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 176,
+   "execution_count": 175,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2744,7 +2747,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 177,
+   "execution_count": 176,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2754,13 +2757,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 178,
-   "metadata": {
-    "collapsed": true,
-    "jupyter": {
-     "outputs_hidden": true
-    }
-   },
+   "execution_count": 177,
+   "metadata": {},
    "outputs": [],
    "source": [
     "np.savez(\"my_arrays\", my_a=a, my_b=b)"
@@ -2775,7 +2773,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 179,
+   "execution_count": 178,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2794,7 +2792,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 180,
+   "execution_count": 179,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2811,7 +2809,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 181,
+   "execution_count": 180,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -2820,7 +2818,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 182,
+   "execution_count": 181,
    "metadata": {},
    "outputs": [],
    "source": [