Add descriptions to interactives (#909)

* LE2 description

* GT3 description

* GT1 interactive descriptions

* add LE1 doenet descriptions

* Upgrade pretext to newer version that handles descriptions for interactives

---------

Co-authored-by: Steven Clontz <steven.clontz@gmail.com>

Author: siwelwerd

requirements.txt

@@ -1,4 +1,4 @@
-pretext == 2.24.0
+pretext == 2.36.0
 CodeChat-Server == 0.2.25
 pelican == 4.11.0
 markdown == 3.7.0

source/linear-algebra/source/01-LE/01.ptx

@@ -240,6 +240,9 @@ Following are some examples of addition and scalar multiplication in <m>\mathbb
           <slate surface="doenetml">
             <xi:include parse="text" href="doenet/LE1-add-vectors.xml"/>
           </slate>
+          <description>
+            <p>An interactive that shows that the sum of any two vectors in the plane results in a vector which is obtained by placing the two vectors end-to-end.</p>
+          </description>
         </interactive>
     </figure>
     <figure xml:id="figure-le1-scalar-mult">
@@ -248,6 +251,9 @@ Following are some examples of addition and scalar multiplication in <m>\mathbb
           <slate surface="doenetml">
             <xi:include parse="text" href="doenet/LE1-scalar-mult.xml"/>
           </slate>
+          <description>
+            <p>An interactive that shows that the scalar multiple of any vector in the plane is the result of lengthening the vector by that factor, and reversing its direction in the case of a negative multiple.</p>
+          </description>
         </interactive>
     </figure>
     <definition>

source/linear-algebra/source/01-LE/02.ptx

@@ -337,6 +337,9 @@ Replace a row with zeros, for example:
           <slate surface="doenetml">
             <xi:include parse="text" href="doenet/LE2-add-rows.xml"/>
           </slate>
+          <description>
+            <p>Interactive applet illustrating geometrically the result of adding multiples of one equation (plane) to another.</p>
+          </description>
         </interactive>
         <p>
 How does adding row multiples to other rows affect a linear system's

source/linear-algebra/source/05-GT/01.ptx

@@ -49,6 +49,10 @@ defined by the standard basic vectors <m>\vec e_1,\vec e_2</m>.
       <slate surface="doenetml">
         <xi:include parse="text" href="doenet/GT1-doenet-transformation.xml"/>
       </slate>
+      <description>
+        <p>Interactive applet allowing users to drag two vectors and geometrically observe the result of applying
+          the linear transformation defined mapping the standard basis vectors to those two vectors.</p>
+      </description>
     </interactive>
   </figure>
 </observation>
@@ -337,6 +341,9 @@ area of resulting parallelogram, what is the value of <m>\det([\vec{e}_1\hspace{
         <slate surface="doenetml">
           <xi:include parse="text" href="doenet/GT1-doenet-duplicate-column.xml"/>
         </slate>
+        <description>
+          <p>Interactive displaying the geometric effect of a linear transformation with two identical columns.</p>
+        </description>
       </interactive>
         <p>Which of the following is true?</p>
   <ol marker="A." cols="2">
@@ -355,6 +362,9 @@ area of resulting parallelogram, what is the value of <m>\det([\vec{e}_1\hspace{
       <slate surface="doenetml">
         <xi:include parse="text" href="doenet/GT1-doenet-scale-column.xml"/>
       </slate>
+        <description>
+          <p>Interactive displaying the geometric effect of scaling a column.</p>
+        </description>
     </interactive>
     <p>
 Which of the following is true?
@@ -380,6 +390,9 @@ parallelogram.
       <slate surface="doenetml">
         <xi:include parse="text" href="doenet/GT1-doenet-add-column.xml"/>
       </slate>
+      <description>
+        <p>Interactive applet illustrating the geometric effect of adding a column to another column.</p>
+      </description>
     </interactive>
     <p>
 Which of the following is true?
@@ -453,6 +466,9 @@ Consider <m>\det([\vec v \hspace{1em}\vec w+c \vec{v}])</m> and
         <slate surface="doenetml">
           <xi:include parse="text" href="doenet/GT1-doenet-add-column-multiples.xml"/>
         </slate>
+      <description>
+        <p>Interactive applet illustrating the geometric effect of adding a multiple of a column to another column.</p>
+      </description>
       </interactive>
 <p>
 The base of both parallelograms is <m>\vec{v}</m>, while the height has not changed,

source/linear-algebra/source/05-GT/03.ptx

@@ -184,6 +184,11 @@ and we call this <m>\lambda</m> an <term>eigenvalue</term><idx>eigenvalue</idx>
       <slate surface="doenetml">
         <xi:include parse="text" href="doenet/GT3-doenet-eigenvector.xml"/>
       </slate>
+      <description>
+        <p>Interactive applet allowing readers to drag two vectors around until they form a set of linearly
+          independent eigenvectors.
+        </p>
+      </description>
     </interactive>
     <p>
       What are the eigenvalues for this matrix?