diff --git a/doc/pub/week36/html/._week36-bs017.html b/doc/pub/week36/html/._week36-bs017.html
index cea60bc4d..0bfe5df46 100644
--- a/doc/pub/week36/html/._week36-bs017.html
+++ b/doc/pub/week36/html/._week36-bs017.html
@@ -307,7 +307,7 @@ $$
 
 <p>Taking the derivative with respect to \( \boldsymbol{\beta} \) and recalling that the derivative of the absolute value is (we drop the boldfaced vector symbol for simplicty)</p>
 $$
-\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\ 0 & \beta =0\\-1 & \beta < 0, \end{array}\right.
+\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\-1 & \beta < 0, \end{array}\right.
 $$
 
 <p>we have that the derivative of the cost function is</p>
diff --git a/doc/pub/week36/html/week36-reveal.html b/doc/pub/week36/html/week36-reveal.html
index 55de599fc..3b4d2e8a7 100644
--- a/doc/pub/week36/html/week36-reveal.html
+++ b/doc/pub/week36/html/week36-reveal.html
@@ -747,7 +747,7 @@ $$
 <p>Taking the derivative with respect to \( \boldsymbol{\beta} \) and recalling that the derivative of the absolute value is (we drop the boldfaced vector symbol for simplicty)</p>
 <p>&nbsp;<br>
 $$
-\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\ 0 & \beta =0\\-1 & \beta < 0, \end{array}\right.
+\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\-1 & \beta < 0, \end{array}\right.
 $$
 <p>&nbsp;<br>
 
diff --git a/doc/pub/week36/html/week36-solarized.html b/doc/pub/week36/html/week36-solarized.html
index 7957d9901..5c028f5ec 100644
--- a/doc/pub/week36/html/week36-solarized.html
+++ b/doc/pub/week36/html/week36-solarized.html
@@ -733,7 +733,7 @@ $$
 
 <p>Taking the derivative with respect to \( \boldsymbol{\beta} \) and recalling that the derivative of the absolute value is (we drop the boldfaced vector symbol for simplicty)</p>
 $$
-\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\ 0 & \beta =0\\-1 & \beta < 0, \end{array}\right.
+\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\-1 & \beta < 0, \end{array}\right.
 $$
 
 <p>we have that the derivative of the cost function is</p>
diff --git a/doc/pub/week36/html/week36.html b/doc/pub/week36/html/week36.html
index 4f955e537..3eebed54f 100644
--- a/doc/pub/week36/html/week36.html
+++ b/doc/pub/week36/html/week36.html
@@ -810,7 +810,7 @@ $$
 
 <p>Taking the derivative with respect to \( \boldsymbol{\beta} \) and recalling that the derivative of the absolute value is (we drop the boldfaced vector symbol for simplicty)</p>
 $$
-\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\ 0 & \beta =0\\-1 & \beta < 0, \end{array}\right.
+\frac{d \vert \beta\vert}{d \boldsymbol{\beta}}=\mathrm{sgn}(\boldsymbol{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\-1 & \beta < 0, \end{array}\right.
 $$
 
 <p>we have that the derivative of the cost function is</p>
diff --git a/doc/pub/week36/ipynb/ipynb-week36-src.tar.gz b/doc/pub/week36/ipynb/ipynb-week36-src.tar.gz
index d49a44846..94b710b4b 100644
Binary files a/doc/pub/week36/ipynb/ipynb-week36-src.tar.gz and b/doc/pub/week36/ipynb/ipynb-week36-src.tar.gz differ
diff --git a/doc/pub/week36/ipynb/week36.ipynb b/doc/pub/week36/ipynb/week36.ipynb
index 0310a0881..d4bae4602 100644
--- a/doc/pub/week36/ipynb/week36.ipynb
+++ b/doc/pub/week36/ipynb/week36.ipynb
@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "0cdf8850",
+   "id": "a1aa9e8e",
    "metadata": {
     "editable": true
    },
@@ -14,7 +14,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d9d934db",
+   "id": "24466970",
    "metadata": {
     "editable": true
    },
@@ -29,7 +29,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "ba07fa12",
+   "id": "c1d2b057",
    "metadata": {
     "editable": true
    },
@@ -52,7 +52,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "63641091",
+   "id": "71f1b443",
    "metadata": {
     "editable": true
    },
@@ -62,7 +62,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f76bdadc",
+   "id": "85a60d6e",
    "metadata": {
     "editable": true
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@@ -72,7 +72,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "5dbb5a76",
+   "id": "408f45c6",
    "metadata": {
     "editable": true
    },
@@ -84,7 +84,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "cfa3082a",
+   "id": "fea6b70c",
    "metadata": {
     "editable": true
    },
@@ -96,7 +96,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "767b7dae",
+   "id": "307fcf10",
    "metadata": {
     "editable": true
    },
@@ -106,7 +106,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b63b6390",
+   "id": "afd487bb",
    "metadata": {
     "editable": true
    },
@@ -118,7 +118,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0c930b23",
+   "id": "0754fc52",
    "metadata": {
     "editable": true
    },
@@ -128,7 +128,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "bb80c091",
+   "id": "c9da24d6",
    "metadata": {
     "editable": true
    },
@@ -145,7 +145,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0c51d644",
+   "id": "882c68ee",
    "metadata": {
     "editable": true
    },
@@ -155,7 +155,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "64fd2556",
+   "id": "f75b89a3",
    "metadata": {
     "editable": true
    },
@@ -167,7 +167,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "614cd695",
+   "id": "420bd711",
    "metadata": {
     "editable": true
    },
@@ -177,7 +177,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d5660434",
+   "id": "a8177320",
    "metadata": {
     "editable": true
    },
@@ -189,7 +189,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "48e6676c",
+   "id": "2b7f7523",
    "metadata": {
     "editable": true
    },
@@ -203,7 +203,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "43feaa3c",
+   "id": "2082a67e",
    "metadata": {
     "editable": true
    },
@@ -215,7 +215,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "5db0b87b",
+   "id": "e937b482",
    "metadata": {
     "editable": true
    },
@@ -237,7 +237,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a43870c2",
+   "id": "cb75b952",
    "metadata": {
     "editable": true
    },
@@ -249,7 +249,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d3252a54",
+   "id": "2d49eefe",
    "metadata": {
     "editable": true
    },
@@ -264,7 +264,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a498c14c",
+   "id": "6890a6f6",
    "metadata": {
     "editable": true
    },
@@ -276,7 +276,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a6451a0a",
+   "id": "5c346d9c",
    "metadata": {
     "editable": true
    },
@@ -288,7 +288,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "bf009aad",
+   "id": "bb72daa0",
    "metadata": {
     "editable": true
    },
@@ -298,7 +298,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2ea85309",
+   "id": "e13f8e81",
    "metadata": {
     "editable": true
    },
@@ -310,7 +310,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "bfe2d95b",
+   "id": "1d3d44bc",
    "metadata": {
     "editable": true
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@@ -320,7 +320,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "3b9679ff",
+   "id": "33a14839",
    "metadata": {
     "editable": true
    },
@@ -332,7 +332,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1b9a2c60",
+   "id": "96acda72",
    "metadata": {
     "editable": true
    },
@@ -342,7 +342,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "758bb517",
+   "id": "d54656fc",
    "metadata": {
     "editable": true
    },
@@ -354,7 +354,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7d1613ac",
+   "id": "953e535b",
    "metadata": {
     "editable": true
    },
@@ -371,7 +371,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "98df490e",
+   "id": "2b4dfcd7",
    "metadata": {
     "editable": true
    },
@@ -385,7 +385,7 @@
   {
    "cell_type": "code",
    "execution_count": 1,
-   "id": "078a6ad8",
+   "id": "ef011801",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -397,7 +397,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6707c726",
+   "id": "7298a620",
    "metadata": {
     "editable": true
    },
@@ -408,7 +408,7 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "id": "370cb3f4",
+   "id": "f57c023e",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -448,7 +448,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0b6972a5",
+   "id": "831154aa",
    "metadata": {
     "editable": true
    },
@@ -468,7 +468,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0de2cb7d",
+   "id": "5e38f1a0",
    "metadata": {
     "editable": true
    },
@@ -480,7 +480,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "23eab89f",
+   "id": "bccf668a",
    "metadata": {
     "editable": true
    },
@@ -491,7 +491,7 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "id": "c3a18a30",
+   "id": "6dbe4733",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -525,7 +525,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b711f160",
+   "id": "fbbb5bf7",
    "metadata": {
     "editable": true
    },
@@ -535,7 +535,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "959ce791",
+   "id": "1b606e5f",
    "metadata": {
     "editable": true
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@@ -548,7 +548,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "39952e85",
+   "id": "92e9b399",
    "metadata": {
     "editable": true
    },
@@ -560,7 +560,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4ab05311",
+   "id": "5282c65c",
    "metadata": {
     "editable": true
    },
@@ -570,7 +570,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "850b5f13",
+   "id": "f374d054",
    "metadata": {
     "editable": true
    },
@@ -583,7 +583,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6bb355ba",
+   "id": "6eb51434",
    "metadata": {
     "editable": true
    },
@@ -593,7 +593,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "61100c4a",
+   "id": "2efb31ec",
    "metadata": {
     "editable": true
    },
@@ -605,7 +605,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "8f88ec32",
+   "id": "3cb8e5b2",
    "metadata": {
     "editable": true
    },
@@ -620,7 +620,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "15f2ef60",
+   "id": "44b4863e",
    "metadata": {
     "editable": true
    },
@@ -633,7 +633,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e38fcb16",
+   "id": "1b75cfde",
    "metadata": {
     "editable": true
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@@ -645,7 +645,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "40fab43f",
+   "id": "6effd6be",
    "metadata": {
     "editable": true
    },
@@ -657,7 +657,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "66a56fba",
+   "id": "d1dc6c09",
    "metadata": {
     "editable": true
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@@ -667,7 +667,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "613124d3",
+   "id": "dd6d67a7",
    "metadata": {
     "editable": true
    },
@@ -680,7 +680,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b546f7b1",
+   "id": "f058b298",
    "metadata": {
     "editable": true
    },
@@ -692,7 +692,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9c37d3a5",
+   "id": "faff16bb",
    "metadata": {
     "editable": true
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@@ -704,7 +704,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f97b69e4",
+   "id": "997d3a45",
    "metadata": {
     "editable": true
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@@ -716,7 +716,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "51c6d3f3",
+   "id": "72eab6bf",
    "metadata": {
     "editable": true
    },
@@ -728,7 +728,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0349e789",
+   "id": "7fa9dd90",
    "metadata": {
     "editable": true
    },
@@ -742,7 +742,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7750b15a",
+   "id": "25f024c7",
    "metadata": {
     "editable": true
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@@ -754,7 +754,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7e7d2e98",
+   "id": "1111f1fd",
    "metadata": {
     "editable": true
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@@ -764,7 +764,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d30bfd0d",
+   "id": "0ed18227",
    "metadata": {
     "editable": true
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@@ -776,7 +776,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "deafdcf7",
+   "id": "3a6ec672",
    "metadata": {
     "editable": true
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@@ -786,7 +786,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "5e21ae6f",
+   "id": "7af71e5c",
    "metadata": {
     "editable": true
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@@ -798,7 +798,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "afec6072",
+   "id": "ad10e79d",
    "metadata": {
     "editable": true
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@@ -810,7 +810,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "50639efe",
+   "id": "54735efc",
    "metadata": {
     "editable": true
    },
@@ -820,7 +820,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "79eda3ec",
+   "id": "b0c646e6",
    "metadata": {
     "editable": true
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@@ -831,7 +831,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "af75fd50",
+   "id": "76a54002",
    "metadata": {
     "editable": true
    },
@@ -843,7 +843,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a2924eb9",
+   "id": "12f9b40e",
    "metadata": {
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@@ -859,7 +859,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "ea618540",
+   "id": "bb1e249c",
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@@ -872,7 +872,7 @@
   },
   {
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-   "id": "483b1b84",
+   "id": "ed9e023d",
    "metadata": {
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@@ -884,7 +884,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "c94305bc",
+   "id": "a688bfaf",
    "metadata": {
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@@ -894,7 +894,7 @@
   },
   {
    "cell_type": "markdown",
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+   "id": "21044335",
    "metadata": {
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@@ -906,7 +906,7 @@
   },
   {
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+   "id": "299f4109",
    "metadata": {
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@@ -916,7 +916,7 @@
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   {
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-   "id": "c69574d8",
+   "id": "1651d9bd",
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@@ -928,7 +928,7 @@
   },
   {
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-   "id": "424e3385",
+   "id": "e83e7789",
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@@ -940,7 +940,7 @@
   },
   {
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+   "id": "ec595af7",
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@@ -956,7 +956,7 @@
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   {
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+   "id": "e0e59dc4",
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@@ -968,7 +968,7 @@
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@@ -980,7 +980,7 @@
   },
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-   "id": "45207aad",
+   "id": "f9036410",
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@@ -990,7 +990,7 @@
   },
   {
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-   "id": "6cfa36e6",
+   "id": "e199f58c",
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@@ -1002,7 +1002,7 @@
   },
   {
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+   "id": "9b3de535",
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@@ -1012,7 +1012,7 @@
   },
   {
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-   "id": "15febc2f",
+   "id": "443439e9",
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@@ -1024,7 +1024,7 @@
   },
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+   "id": "55cb8604",
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@@ -1041,7 +1041,7 @@
   },
   {
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-   "id": "49c6198d",
+   "id": "ad142b9b",
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@@ -1053,7 +1053,7 @@
   },
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-   "id": "45f10898",
+   "id": "05563f89",
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@@ -1065,7 +1065,7 @@
   },
   {
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-   "id": "b8bcf5be",
+   "id": "476b7d47",
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@@ -1075,19 +1075,19 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a765de73",
+   "id": "692ca09c",
    "metadata": {
     "editable": true
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    "source": [
     "$$\n",
-    "\\frac{d \\vert \\beta\\vert}{d \\boldsymbol{\\beta}}=\\mathrm{sgn}(\\boldsymbol{\\beta})=\\left\\{\\begin{array}{cc} 1 & \\beta > 0 \\\\ 0 & \\beta =0\\\\-1 & \\beta < 0, \\end{array}\\right.\n",
+    "\\frac{d \\vert \\beta\\vert}{d \\boldsymbol{\\beta}}=\\mathrm{sgn}(\\boldsymbol{\\beta})=\\left\\{\\begin{array}{cc} 1 & \\beta > 0 \\\\-1 & \\beta < 0, \\end{array}\\right.\n",
     "$$"
    ]
   },
   {
    "cell_type": "markdown",
-   "id": "1ae99b8c",
+   "id": "7bfae2eb",
    "metadata": {
     "editable": true
    },
@@ -1097,7 +1097,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4d212885",
+   "id": "2608b6ad",
    "metadata": {
     "editable": true
    },
@@ -1109,7 +1109,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a9adf93f",
+   "id": "b50f3075",
    "metadata": {
     "editable": true
    },
@@ -1119,7 +1119,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4c2d3089",
+   "id": "136e99ca",
    "metadata": {
     "editable": true
    },
@@ -1131,7 +1131,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "21116278",
+   "id": "54834ded",
    "metadata": {
     "editable": true
    },
@@ -1141,7 +1141,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0d41cfb1",
+   "id": "e57a4ccc",
    "metadata": {
     "editable": true
    },
@@ -1156,7 +1156,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e40f4b26",
+   "id": "ab5884ef",
    "metadata": {
     "editable": true
    },
@@ -1168,7 +1168,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "856b6c5d",
+   "id": "0acb08a2",
    "metadata": {
     "editable": true
    },
@@ -1178,7 +1178,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "54e20521",
+   "id": "897d6754",
    "metadata": {
     "editable": true
    },
@@ -1190,7 +1190,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "648c54a9",
+   "id": "3cfb28f3",
    "metadata": {
     "editable": true
    },
@@ -1202,7 +1202,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "94f6bb27",
+   "id": "a4b2284f",
    "metadata": {
     "editable": true
    },
@@ -1214,7 +1214,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e96357ae",
+   "id": "38a2d365",
    "metadata": {
     "editable": true
    },
@@ -1224,7 +1224,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a850913f",
+   "id": "13fabfcc",
    "metadata": {
     "editable": true
    },
@@ -1236,7 +1236,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "956f0df6",
+   "id": "07aa0e3c",
    "metadata": {
     "editable": true
    },
@@ -1248,7 +1248,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "00489e2e",
+   "id": "fa2f1b9e",
    "metadata": {
     "editable": true
    },
@@ -1260,7 +1260,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b309c44e",
+   "id": "89ba0131",
    "metadata": {
     "editable": true
    },
@@ -1270,7 +1270,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "68508004",
+   "id": "29ff16bd",
    "metadata": {
     "editable": true
    },
@@ -1282,7 +1282,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "04616651",
+   "id": "2604db78",
    "metadata": {
     "editable": true
    },
@@ -1292,7 +1292,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9a1ef57e",
+   "id": "9afd4098",
    "metadata": {
     "editable": true
    },
@@ -1306,7 +1306,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "bdbd4368",
+   "id": "67502ce2",
    "metadata": {
     "editable": true
    },
@@ -1316,7 +1316,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "32d47fbe",
+   "id": "60f8b410",
    "metadata": {
     "editable": true
    },
@@ -1328,7 +1328,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1cd0ded0",
+   "id": "542d2f5b",
    "metadata": {
     "editable": true
    },
@@ -1340,7 +1340,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "df02010d",
+   "id": "4a1acd30",
    "metadata": {
     "editable": true
    },
@@ -1350,7 +1350,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f05831be",
+   "id": "ca8bfb12",
    "metadata": {
     "editable": true
    },
@@ -1362,7 +1362,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d4a0902c",
+   "id": "edb2effa",
    "metadata": {
     "editable": true
    },
@@ -1372,7 +1372,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "45637d5c",
+   "id": "c4209ea6",
    "metadata": {
     "editable": true
    },
@@ -1384,7 +1384,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a163edc5",
+   "id": "d0cc7d06",
    "metadata": {
     "editable": true
    },
@@ -1396,7 +1396,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a231c715",
+   "id": "5a85b8ab",
    "metadata": {
     "editable": true
    },
@@ -1406,7 +1406,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "dd6e0659",
+   "id": "05dcc6eb",
    "metadata": {
     "editable": true
    },
@@ -1418,7 +1418,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4244c122",
+   "id": "ed3d4c97",
    "metadata": {
     "editable": true
    },
@@ -1428,7 +1428,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b242d797",
+   "id": "9c02a8a2",
    "metadata": {
     "editable": true
    },
@@ -1440,7 +1440,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "50a7f72b",
+   "id": "ec6a1a82",
    "metadata": {
     "editable": true
    },
@@ -1452,7 +1452,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2a4e6de8",
+   "id": "5dc83dc7",
    "metadata": {
     "editable": true
    },
@@ -1462,7 +1462,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7a65e4bf",
+   "id": "b980a838",
    "metadata": {
     "editable": true
    },
@@ -1474,7 +1474,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e722cc79",
+   "id": "eb17a435",
    "metadata": {
     "editable": true
    },
@@ -1487,7 +1487,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "3649d720",
+   "id": "5bf5ade1",
    "metadata": {
     "editable": true
    },
@@ -1499,7 +1499,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "587f2ca7",
+   "id": "1aa52485",
    "metadata": {
     "editable": true
    },
@@ -1511,7 +1511,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "45b5723f",
+   "id": "ae6a1b38",
    "metadata": {
     "editable": true
    },
@@ -1523,7 +1523,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "bbdd22e6",
+   "id": "15581c34",
    "metadata": {
     "editable": true
    },
@@ -1533,7 +1533,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2cef5397",
+   "id": "e4062e9a",
    "metadata": {
     "editable": true
    },
@@ -1545,7 +1545,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7bd0268b",
+   "id": "2486c58b",
    "metadata": {
     "editable": true
    },
@@ -1555,7 +1555,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "65b6b53d",
+   "id": "a6c34715",
    "metadata": {
     "editable": true
    },
@@ -1567,7 +1567,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "625d24a5",
+   "id": "ffafb4bc",
    "metadata": {
     "editable": true
    },
@@ -1577,7 +1577,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "58f4ce01",
+   "id": "f759d4d9",
    "metadata": {
     "editable": true
    },
@@ -1589,7 +1589,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b94811e3",
+   "id": "da461bab",
    "metadata": {
     "editable": true
    },
@@ -1599,7 +1599,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "448bae58",
+   "id": "d651a0c9",
    "metadata": {
     "editable": true
    },
@@ -1612,7 +1612,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d8c14f06",
+   "id": "21e67c82",
    "metadata": {
     "editable": true
    },
@@ -1624,7 +1624,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f2f73ca3",
+   "id": "9a399a31",
    "metadata": {
     "editable": true
    },
@@ -1636,7 +1636,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "10cef1ce",
+   "id": "ab59761a",
    "metadata": {
     "editable": true
    },
@@ -1646,7 +1646,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a2112a52",
+   "id": "b73eeed1",
    "metadata": {
     "editable": true
    },
@@ -1658,7 +1658,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b0d86244",
+   "id": "772166c2",
    "metadata": {
     "editable": true
    },
@@ -1675,7 +1675,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6673beb0",
+   "id": "726f74f5",
    "metadata": {
     "editable": true
    },
@@ -1687,7 +1687,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "59e81bbe",
+   "id": "ee4db540",
    "metadata": {
     "editable": true
    },
@@ -1699,7 +1699,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a0d67bfc",
+   "id": "59321bd1",
    "metadata": {
     "editable": true
    },
@@ -1709,7 +1709,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "156f61c0",
+   "id": "62eb0c08",
    "metadata": {
     "editable": true
    },
@@ -1721,7 +1721,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7df32550",
+   "id": "5aab8a9f",
    "metadata": {
     "editable": true
    },
@@ -1731,7 +1731,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9d053eba",
+   "id": "ef30cf7d",
    "metadata": {
     "editable": true
    },
@@ -1743,7 +1743,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "34b407f7",
+   "id": "07204512",
    "metadata": {
     "editable": true
    },
@@ -1753,7 +1753,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "22558e22",
+   "id": "72553340",
    "metadata": {
     "editable": true
    },
@@ -1765,7 +1765,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0f4356ee",
+   "id": "713ec80a",
    "metadata": {
     "editable": true
    },
@@ -1775,7 +1775,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1a9692af",
+   "id": "4f5de407",
    "metadata": {
     "editable": true
    },
@@ -1790,7 +1790,7 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "id": "cdd36c16",
+   "id": "904936a6",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -1852,7 +1852,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f7ccd903",
+   "id": "dcc0849f",
    "metadata": {
     "editable": true
    },
@@ -1862,7 +1862,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "44b83eed",
+   "id": "70914368",
    "metadata": {
     "editable": true
    },
@@ -1873,7 +1873,7 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "id": "6143cd67",
+   "id": "b4449e13",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -1940,7 +1940,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a50d4975",
+   "id": "b11cbe1a",
    "metadata": {
     "editable": true
    },
@@ -1951,7 +1951,7 @@
   {
    "cell_type": "code",
    "execution_count": 6,
-   "id": "70f5ae5b",
+   "id": "fb24a373",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -2040,7 +2040,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "70ebb3a5",
+   "id": "2017a597",
    "metadata": {
     "editable": true
    },
@@ -2068,7 +2068,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4591f8dd",
+   "id": "94e0c405",
    "metadata": {
     "editable": true
    },
@@ -2103,7 +2103,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "09d7dcdc",
+   "id": "9a3e8398",
    "metadata": {
     "editable": true
    },
@@ -2117,7 +2117,7 @@
   {
    "cell_type": "code",
    "execution_count": 7,
-   "id": "685286a8",
+   "id": "e516e2d0",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -2142,7 +2142,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "683c3895",
+   "id": "f7fa07c3",
    "metadata": {
     "editable": true
    },
@@ -2158,7 +2158,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "dff77d42",
+   "id": "dce81449",
    "metadata": {
     "editable": true
    },
@@ -2170,7 +2170,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9544c1de",
+   "id": "ce2dcd78",
    "metadata": {
     "editable": true
    },
@@ -2185,7 +2185,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9d7a819f",
+   "id": "3fccce9a",
    "metadata": {
     "editable": true
    },
@@ -2197,7 +2197,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "82eecc7d",
+   "id": "de26a126",
    "metadata": {
     "editable": true
    },
@@ -2207,7 +2207,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9cead3ff",
+   "id": "f3288af2",
    "metadata": {
     "editable": true
    },
@@ -2219,7 +2219,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1a42de96",
+   "id": "326e9cc2",
    "metadata": {
     "editable": true
    },
@@ -2229,7 +2229,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4039550e",
+   "id": "f21c069e",
    "metadata": {
     "editable": true
    },
@@ -2241,7 +2241,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "061c0925",
+   "id": "9f96ff2a",
    "metadata": {
     "editable": true
    },
@@ -2254,7 +2254,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0ef71aaa",
+   "id": "27015157",
    "metadata": {
     "editable": true
    },
@@ -2266,7 +2266,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b84783db",
+   "id": "297e6147",
    "metadata": {
     "editable": true
    },
@@ -2276,7 +2276,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0e6a90d7",
+   "id": "f6a33ae5",
    "metadata": {
     "editable": true
    },
@@ -2288,7 +2288,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "cc1e7510",
+   "id": "b25ed742",
    "metadata": {
     "editable": true
    },
@@ -2298,7 +2298,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "09d043b0",
+   "id": "aee30f10",
    "metadata": {
     "editable": true
    },
@@ -2310,7 +2310,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "005ff4e4",
+   "id": "3698fea1",
    "metadata": {
     "editable": true
    },
@@ -2320,7 +2320,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1c4638da",
+   "id": "3ef9bd66",
    "metadata": {
     "editable": true
    },
@@ -2332,7 +2332,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "630cec28",
+   "id": "00a62bd4",
    "metadata": {
     "editable": true
    },
@@ -2342,7 +2342,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "ffd02bde",
+   "id": "a2119068",
    "metadata": {
     "editable": true
    },
@@ -2354,7 +2354,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e48a1d51",
+   "id": "cec69673",
    "metadata": {
     "editable": true
    },
@@ -2364,7 +2364,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "e21c575e",
+   "id": "04251039",
    "metadata": {
     "editable": true
    },
@@ -2376,7 +2376,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "fe6232b8",
+   "id": "dbbae452",
    "metadata": {
     "editable": true
    },
@@ -2386,7 +2386,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "5f048e0d",
+   "id": "81a101ab",
    "metadata": {
     "editable": true
    },
@@ -2398,7 +2398,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2dfe8421",
+   "id": "a45ecb54",
    "metadata": {
     "editable": true
    },
@@ -2410,7 +2410,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1da8bac7",
+   "id": "e6cf589d",
    "metadata": {
     "editable": true
    },
@@ -2422,7 +2422,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "311d9718",
+   "id": "0550c162",
    "metadata": {
     "editable": true
    },
@@ -2435,7 +2435,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "c321d8e5",
+   "id": "17cd21db",
    "metadata": {
     "editable": true
    },
@@ -2447,7 +2447,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "abb5259d",
+   "id": "e0b44f48",
    "metadata": {
     "editable": true
    },
@@ -2457,7 +2457,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d2a01313",
+   "id": "71a85aca",
    "metadata": {
     "editable": true
    },
@@ -2471,7 +2471,7 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "id": "a6ed191e",
+   "id": "5e5404b9",
    "metadata": {
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@@ -2568,7 +2568,7 @@
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@@ -2589,7 +2589,7 @@
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@@ -2601,7 +2601,7 @@
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@@ -2611,7 +2611,7 @@
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@@ -2623,7 +2623,7 @@
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@@ -2633,7 +2633,7 @@
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@@ -2645,7 +2645,7 @@
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@@ -2655,7 +2655,7 @@
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@@ -2668,7 +2668,7 @@
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@@ -2744,7 +2744,7 @@
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@@ -2757,7 +2757,7 @@
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@@ -2768,7 +2768,7 @@
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@@ -2857,7 +2857,7 @@
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@@ -2874,7 +2874,7 @@
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@@ -2884,7 +2884,7 @@
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@@ -2913,7 +2913,7 @@
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@@ -2929,7 +2929,7 @@
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@@ -2948,7 +2948,7 @@
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@@ -2962,7 +2962,7 @@
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@@ -2974,7 +2974,7 @@
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@@ -2985,7 +2985,7 @@
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@@ -2997,7 +2997,7 @@
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@@ -3009,7 +3009,7 @@
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@@ -3025,7 +3025,7 @@
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@@ -3036,7 +3036,7 @@
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@@ -3059,7 +3059,7 @@
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@@ -3070,7 +3070,7 @@
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@@ -3082,7 +3082,7 @@
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@@ -3094,7 +3094,7 @@
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@@ -3108,7 +3108,7 @@
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@@ -3139,7 +3139,7 @@
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@@ -3161,7 +3161,7 @@
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@@ -3173,7 +3173,7 @@
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@@ -3186,7 +3186,7 @@
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@@ -3198,7 +3198,7 @@
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@@ -3210,7 +3210,7 @@
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@@ -3222,7 +3222,7 @@
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@@ -3234,7 +3234,7 @@
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@@ -3257,7 +3257,7 @@
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@@ -3269,7 +3269,7 @@
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@@ -3282,7 +3282,7 @@
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@@ -3294,7 +3294,7 @@
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@@ -3306,7 +3306,7 @@
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@@ -3318,7 +3318,7 @@
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@@ -3329,7 +3329,7 @@
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@@ -3341,7 +3341,7 @@
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@@ -3352,7 +3352,7 @@
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@@ -3364,7 +3364,7 @@
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@@ -3374,7 +3374,7 @@
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@@ -3405,7 +3405,7 @@
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@@ -3417,7 +3417,7 @@
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@@ -3429,7 +3429,7 @@
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@@ -3439,7 +3439,7 @@
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@@ -3451,7 +3451,7 @@
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@@ -3461,7 +3461,7 @@
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@@ -3473,7 +3473,7 @@
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@@ -3483,7 +3483,7 @@
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@@ -3495,7 +3495,7 @@
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@@ -3505,7 +3505,7 @@
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@@ -3525,7 +3525,7 @@
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@@ -3537,7 +3537,7 @@
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@@ -3547,7 +3547,7 @@
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@@ -3559,7 +3559,7 @@
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@@ -3571,7 +3571,7 @@
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@@ -3583,7 +3583,7 @@
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@@ -3595,7 +3595,7 @@
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@@ -3607,7 +3607,7 @@
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@@ -3619,7 +3619,7 @@
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@@ -3631,7 +3631,7 @@
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@@ -3643,7 +3643,7 @@
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@@ -3653,7 +3653,7 @@
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@@ -3665,7 +3665,7 @@
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@@ -3675,7 +3675,7 @@
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@@ -3694,7 +3694,7 @@
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@@ -3715,7 +3715,7 @@
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@@ -3727,7 +3727,7 @@
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@@ -3738,7 +3738,7 @@
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@@ -3751,7 +3751,7 @@
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@@ -3763,7 +3763,7 @@
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@@ -3773,7 +3773,7 @@
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@@ -3785,7 +3785,7 @@
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@@ -3795,7 +3795,7 @@
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@@ -3807,7 +3807,7 @@
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@@ -3817,7 +3817,7 @@
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@@ -3834,7 +3834,7 @@
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@@ -3853,7 +3853,7 @@
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@@ -3927,7 +3927,7 @@
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@@ -3937,7 +3937,7 @@
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@@ -3951,7 +3951,7 @@
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@@ -3963,7 +3963,7 @@
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@@ -3973,7 +3973,7 @@
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@@ -3985,7 +3985,7 @@
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@@ -3995,7 +3995,7 @@
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@@ -4007,7 +4007,7 @@
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@@ -4017,7 +4017,7 @@
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@@ -4029,7 +4029,7 @@
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@@ -4039,7 +4039,7 @@
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@@ -4055,7 +4055,7 @@
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@@ -4067,7 +4067,7 @@
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@@ -4077,7 +4077,7 @@
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@@ -4089,7 +4089,7 @@
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@@ -4102,7 +4102,7 @@
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    "cell_type": "markdown",
-   "id": "e82314b6",
+   "id": "153f9fb1",
    "metadata": {
     "editable": true
    },
@@ -4114,7 +4114,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "b41cfd8c",
+   "id": "ff218a85",
    "metadata": {
     "editable": true
    },
@@ -4124,7 +4124,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d69fa87c",
+   "id": "2232ec62",
    "metadata": {
     "editable": true
    },
@@ -4136,7 +4136,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "f3a6599c",
+   "id": "1bd64229",
    "metadata": {
     "editable": true
    },
@@ -4146,7 +4146,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "d9dd353c",
+   "id": "56621d5e",
    "metadata": {
     "editable": true
    },
@@ -4158,7 +4158,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "cd93eb96",
+   "id": "d7f8d368",
    "metadata": {
     "editable": true
    },
@@ -4170,7 +4170,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6f58dfb8",
+   "id": "88cfc93e",
    "metadata": {
     "editable": true
    },
@@ -4180,7 +4180,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "fd6d45ce",
+   "id": "aaad23a8",
    "metadata": {
     "editable": true
    },
@@ -4192,7 +4192,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "68b48684",
+   "id": "3bec64a8",
    "metadata": {
     "editable": true
    },
@@ -4204,7 +4204,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "27195bf0",
+   "id": "add848cd",
    "metadata": {
     "editable": true
    },
@@ -4216,7 +4216,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "1233905b",
+   "id": "a3b45d0c",
    "metadata": {
     "editable": true
    },
@@ -4226,7 +4226,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0e4f29b3",
+   "id": "93f5243d",
    "metadata": {
     "editable": true
    },
@@ -4238,7 +4238,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "233a690d",
+   "id": "364f671e",
    "metadata": {
     "editable": true
    },
@@ -4248,7 +4248,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a29dfa6e",
+   "id": "280a2680",
    "metadata": {
     "editable": true
    },
@@ -4264,7 +4264,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "95c0346f",
+   "id": "ae0be95c",
    "metadata": {
     "editable": true
    },
@@ -4276,7 +4276,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6c1ecc86",
+   "id": "23f1151b",
    "metadata": {
     "editable": true
    },
@@ -4287,7 +4287,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "08246d97",
+   "id": "78ec5686",
    "metadata": {
     "editable": true
    },
@@ -4299,7 +4299,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "42ebfdbf",
+   "id": "598c9feb",
    "metadata": {
     "editable": true
    },
@@ -4309,7 +4309,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a2a32f8c",
+   "id": "4fdc8126",
    "metadata": {
     "editable": true
    },
@@ -4320,7 +4320,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9b40d45b",
+   "id": "56c2de03",
    "metadata": {
     "editable": true
    },
@@ -4334,7 +4334,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2b76e3e0",
+   "id": "face5bab",
    "metadata": {
     "editable": true
    },
@@ -4345,7 +4345,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "8a46c75c",
+   "id": "21e885de",
    "metadata": {
     "editable": true
    },
@@ -4358,7 +4358,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "91563fe5",
+   "id": "5a0d33da",
    "metadata": {
     "editable": true
    },
@@ -4369,7 +4369,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "63ccfb4e",
+   "id": "d115463f",
    "metadata": {
     "editable": true
    },
@@ -4380,7 +4380,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "080297f3",
+   "id": "5404e28a",
    "metadata": {
     "editable": true
    },
@@ -4392,7 +4392,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "447f3096",
+   "id": "d1da9d7f",
    "metadata": {
     "editable": true
    },
@@ -4403,7 +4403,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "0a9f0bb3",
+   "id": "0e5b30de",
    "metadata": {
     "editable": true
    },
@@ -4417,7 +4417,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "4071a161",
+   "id": "0c60c206",
    "metadata": {
     "editable": true
    },
@@ -4443,7 +4443,7 @@
   {
    "cell_type": "code",
    "execution_count": 12,
-   "id": "17e44550",
+   "id": "45553bd2",
    "metadata": {
     "collapsed": false,
     "editable": true
@@ -4456,7 +4456,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "71f71e65",
+   "id": "6f402a22",
    "metadata": {
     "editable": true
    },
@@ -4467,7 +4467,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "aca534d5",
+   "id": "e7d0e01d",
    "metadata": {
     "editable": true
    },
diff --git a/doc/src/week36/week36.do.txt b/doc/src/week36/week36.do.txt
index d3e42da6f..5c04b43ef 100644
--- a/doc/src/week36/week36.do.txt
+++ b/doc/src/week36/week36.do.txt
@@ -462,7 +462,7 @@ C(\bm{X},\bm{\beta})=\left\{(\bm{y}-\bm{X}\bm{\beta})^T(\bm{y}-\bm{X}\bm{\beta})
 Taking the derivative with respect to $\bm{\beta}$ and recalling that the derivative of the absolute value is (we drop the boldfaced vector symbol for simplicty)
 !bt
 \[
-\frac{d \vert \beta\vert}{d \bm{\beta}}=\mathrm{sgn}(\bm{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\ 0 & \beta =0\\-1 & \beta < 0, \end{array}\right.
+\frac{d \vert \beta\vert}{d \bm{\beta}}=\mathrm{sgn}(\bm{\beta})=\left\{\begin{array}{cc} 1 & \beta > 0 \\-1 & \beta < 0, \end{array}\right.
 \]
 !et
 we have that the derivative of the cost function is