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+<page xmlns="http://projectmallard.org/1.0/"
+ type="guide"
+ id="variable">
+
+ <info>
+ <link type="guide" xref="index#equation"/>
+ </info>
+
+ <title>Variables</title>
+ 
+ <p>
+ To assign a value to a variable use the = symbol or choose the variable to assign to with the <gui>→R</gui> button in <link xref="mouse">advanced mode</link>.
+ A variable name must only contain upper or lower characters.
+ </p>
+ <example>
+ <p>
+ x=5
+ </p>
+ <p>
+ value=82
+ </p>
+ </example>
+ <p>
+ Variables can be used in any equation and are substituted for their assigned value.
+ Variables can be inserted using the <gui>←R</gui> button.
+ </p>
+ <example>
+ <p>
+ 6x+3
+ </p>
+ <p>
+ xy−3x+7y−21
+ </p>
+ </example>
+ <p>
+ The following variables are always defined.
+ </p>
+ <table>
+ <tr>
+ <td><p>ans</p></td>
+ <td><p>Result of previous calculation</p></td>
+ </tr>
+ <tr>
+ <td><p>e</p></td>
+ <td><p><link xref="logarithm">Euler's Number</link></p></td>
+ </tr>
+ <tr>
+ <td><p>π</p></td>
+ <td><p><link xref="trigonometry">Pi</link></p></td>
+ </tr>
+ <tr>
+ <td><p>rand</p></td>
+ <td><p>Random value in the range [0,1] (changes on each read)</p></td>
+ </tr>
+ </table>
+</page>