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<page xmlns="http://projectmallard.org/1.0/" type="guide" id="variable" xml:lang="ca">

    <info>
        <link type="guide" xref="index#equation"/>
    
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Joan Duran</mal:name>
      <mal:email>jodufi@gmail.com</mal:email>
      <mal:years>2008</mal:years>
    </mal:credit>
  
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Sergi Morraja</mal:name>
      <mal:email>sergi256@gmail.com</mal:email>
      <mal:years>2011, 2012</mal:years>
    </mal:credit>
  
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Gil Forcada</mal:name>
      <mal:email>gilforcada@guifi.net</mal:email>
      <mal:years>2013</mal:years>
    </mal:credit>
  
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Miquel-Àngel Burgos i Fradeja</mal:name>
      <mal:email>miquel.angel.burgos@gmail.com</mal:email>
      <mal:years>2020</mal:years>
    </mal:credit>
  
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Victor Dargallo</mal:name>
      <mal:email>victordargallo@disroot.org</mal:email>
      <mal:years>2025</mal:years>
    </mal:credit>
  </info>

	<title>Variables and Constants</title>
    
    <p>
    To assign a value to a variable use the = symbol or choose the variable to assign to with the <gui>x</gui> button in <link xref="mouse">advanced mode</link>.
    A variable name must only contain upper or lower case characters, or underscores.
    </p>
    <example>
    <p>x=5</p>
    <p>exemple=82</p>
    </example>
    <p>
    Variables and constants can be used in any equation and are substituted for their assigned value.
    Variables and constants can be inserted using the <gui>x</gui> button.
    </p>
    <example>
    <p>6x+3</p>
    <p>xy−3x+7y−21</p>
    </example>
    <p>Les variables següents sempre estan definides.</p>
    <table>
    <tr>
    <td><p>_</p></td>
    <td><p>Resultat del càlcul anterior</p></td>
    </tr>
    <tr>
    <td><p>rand</p></td>
    <td><p>Valor aleatori en el rang [0,1] (canvia en cada lectura)</p></td>
    </tr>
    </table>
    <p>
    The following constants are always defined.
    </p>
    <table>
    <tr>
    <td colspan="2"><p>Matemàtiques</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>τ</p></td>
    <td><p><link xref="trigonometry">Tau</link></p></td>
    </tr>
    <tr>
    <td><p>φ</p></td>
    <td><p>Raó àuria</p></td>
    </tr>
    <tr>
    <td colspan="2"><p>Electromagnetisme</p></td>
    </tr>
    <tr>
    <td><p>c₀</p></td>
    <td><p>Velocitat de la llum</p></td>
    </tr>
    <tr>
    <td><p>е</p></td>
    <td><p>Càrrega elemental</p></td>
    </tr>
    <tr>
    <td><p>Z₀</p></td>
    <td><p>Impedància del buit</p></td>
    </tr>
    <tr>
    <td><p>μ₀</p></td>
    <td><p>Permeabilitat del buit</p></td>
    </tr>
    <tr>
    <td><p>ε₀</p></td>
    <td><p>Permitivitat del buit</p></td>
    </tr>
    <tr>
    <td colspan="2"><p>Atomic &amp; Nuclear</p></td>
    </tr>
    <tr>
    <td><p>h</p></td>
    <td><p>Planck’s Constant</p></td>
    </tr>
    <tr>
    <td><p>α</p></td>
    <td><p>Fine-Structure Constant</p></td>
    </tr>
    <tr>
    <td><p>mₑ</p></td>
    <td><p>Massa de l'electró</p></td>
    </tr>
    <tr>
    <td><p>mₚ</p></td>
    <td><p>Massa del protó</p></td>
    </tr>
    <tr>
    <td colspan="2"><p>Termodinàmica</p></td>
    </tr>
    <tr>
    <td><p>k</p></td>
    <td><p>Constant de Boltzmann</p></td>
    </tr>
    <tr>
    <td><p>mᵤ</p></td>
    <td><p>Unitat de massa atòmica</p></td>
    </tr>
    <tr>
    <td><p>R</p></td>
    <td><p>Molar Gas Constant</p></td>
    </tr>
    <tr>
    <td><p>σ</p></td>
    <td><p>Constant de Stefan-Boltzmann</p></td>
    </tr>
    <tr>
    <td><p>Nᴀ</p></td>
    <td><p>Avogadro’s Number</p></td>
    </tr>
    <tr>
    <td colspan="2"><p>Gravitació</p></td>
    </tr>
    <tr>
    <td><p>G</p></td>
    <td><p>Constant gravitacional</p></td>
    </tr>
    <tr>
    <td><p>g</p></td>
    <td><p>Acceleració de la Terra</p></td>
    </tr>
    </table>
</page>
