[LON-CAPA-users] How to write a custom response problem with vector I/O?

[Itay]

Hi

I am trying to develop a custom response problem in which the student submission is a vector.
A minimal example is provided below.
Regardless of what I typed in the either of the two input fields I get the response:
'This question expects a numeric answer.'

Please advise what am I doing wrong?

Thanks in advance.
Itay


<problem>  <!-- begin minimal -->
  <script type="loncapa/perl">
    $ax = &random(1.0, 10, 0.1); # Coordinates of \vec{a}
    $ay = &random(1.0, 10, 0.1);
  </script>

  <startouttext />
  Consider a vector <m eval="on">\( \vec{a} = $ax\hat{x} + $ay\hat{y} \)</m>'.
  Provide a vector <m>\( \vec{b} \)</m>, orthogonal to <m>\( \vec{a} \)</m>.
  <br />
  <endouttext />

  <customresponse id="dotProd">
    <answer type="loncapa/perl">
      for ($i=0; $i<2; $i++) {                # Test input sanity.
        if ($submission[i] =~ /^\d+\s+\w+$/) { return 'UNIT_NOTNEEDED'; }
        if ($submission[i] !~ /^[\d\.]+$/)   { return 'WANTED_NUMERIC'; }
      }

      # Is submission correct?
      $dotProd = $ax * $submission[0] + $ay * $submission[1];
      if (abs($dotProd) < 1.0e-3) { return 'APPROX_ANS'; }  # Can't expect EXACT_ANS.
      return 'INCORRECT';
    </answer>

    <startouttext /><m>\( b_x = \)</m><endouttext />
    <textline size="10" readonly="no" spellcheck="none" />
    <startouttext /><br /><endouttext />

    <startouttext /><m>\( b_y = \)</m><endouttext />
    <textline size="10" readonly="no" spellcheck="none" />
    <startouttext /><br /><endouttext />
  </customresponse>
</problem>  <!-- end minimal -->

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