Formula Equation Input
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  Tag: ``<formulaequationinput />``

The formula equation input is a math input type used with Numerical and Formula
responses. It is comparable to a ``<textline math="1"/>`` but with a different
means to display the math. It lets the platform validate the student's input as
she types.

This is achieved by periodically sending the typed expression and requesting
its preview from the LMS. It parses the expression (using the same method as 
when it actually grades), and sends back an OK'd copy.

The basic appearance is that of a textbox with a preview box below it. The
student types in math (see note below for syntax), and a typeset preview
appears below it. Even complicated math expressions may be entered in.

For more information about the syntax, look in the course author's
documentation, under appendix E, the section about Numerical Responses.

Format
******

The XML is rather simple, it is a ``<formulaequationinput/>`` tag with an
optional ``size`` attribute. Unlike ``<textline/>``, there is no ``math``
attribute and adding such will have no effect.

To see an example of the input type in context:

.. code-block:: xml

  <problem>
    <p>What base is the decimal numeral system in?</p>
    <numericalresponse answer="10">
      <formulaequationinput />
    </numericalresponse>

    <p>Write an expression for the product of R_1, R_2, and the inverse of R_3.</p>
    <formularesponse type="ci" samples="R_1,R_2,R_3@1,2,3:3,4,5#10" answer="R_1*R_2/R_3">
      <responseparam type="tolerance" default="0.00001"/> 
      <formulaequationinput size="40" />
    </formularesponse>
  </problem>
