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File:  [LON-CAPA] / loncom / homework / templates / customhints.problem
Revision 1.3: download - view: text, annotated - select for diffs
Sun Oct 31 12:33:08 2010 UTC (14 years, 2 months ago) by www
Branches: MAIN
CVS tags: version_2_12_X, version_2_11_X, version_2_11_5_msu, version_2_11_5, version_2_11_4_uiuc, version_2_11_4_msu, version_2_11_4, version_2_11_3_uiuc, version_2_11_3_msu, version_2_11_3, version_2_11_2_uiuc, version_2_11_2_msu, version_2_11_2_educog, version_2_11_2, version_2_11_1, version_2_11_0_RC3, version_2_11_0_RC2, version_2_11_0_RC1, version_2_11_0, version_2_10_X, version_2_10_1, version_2_10_0_RC2, version_2_10_0, loncapaMITrelate_1, language_hyphenation_merge, language_hyphenation, HEAD, BZ4492-merge, BZ4492-feature_horizontal_radioresponse, BZ4492-feature_Support_horizontal_radioresponse, BZ4492-Support_horizontal_radioresponse
Better return codes

<problem>
<script type="loncapa/perl"># Construct an Egyptian Fraction that can be represented by three terms with denominators between 3 and 12
@denominators=(&random_permutation(&random(1,1000,1),(3..12)))[0..2];
$egyptian='1/'.(join('+1/',sort{$a<=>$b}(@denominators)));
$possible="A possible solution is $egyptian";

# Let the CAS figure out the value
$solution=&cas('maxima',$egyptian);

# Subroutine that checks if the provided term is indeed an Egyptian Fraction
sub analyze {
    my ($expression)=@_;
    $expression=~s/\s//gs;
    $expression=~s/\+?1\//\,/gs;
     if ($expression=~/^(\,[0-9]+)+$/) {
# Format is indeed 1/n+1/m+...
        $last=-1;
        foreach $number (sort { $a<=>$b } split(/\,/,$expression)) {
# Is a number used twice?
             if ($last==$number) { return(0,1); }
             $last=$number;
          }
          return(0,0);
     }
     return(1,0);
}
</script>

<startouttext />

Write $solution as an Egyptian Fraction<br />
<endouttext />

<customresponse answerdisplay="$possible" id="11">
    <answer type="loncapa/perl"># Analyze the format
($formaterror,$doubleerror)=&analyze($submission);
if ($formaterror || $doubleerror) { return 'WRONG_FORMAT'; }
# It is an Egyptian Fraction, is the value correct?
if (&cas('maxima',$submission.'-('.$egyptian.')') eq '0') {
    return 'EXACT_ANS';
}
return 'INCORRECT';</answer>
    <textline readonly="no" size="40" />

 <customhint name="format" id="12">
      <answer type="loncapa/perl">if ((&analyze($submission))[0]) { return 'EXACT_ANS'; }
return 'INCORRECT';</answer>
</customhint>
<hintpart on="format">
<startouttext />
<p>
Egyptian Fractions have a format of 1/number+1/number+..., for example 1/3+1/17+1/52. 
</p>
<endouttext />
</hintpart>
 <customhint name="double" id="13">
      <answer type="loncapa/perl">if ((&analyze($submission))[1]) { return 'EXACT_ANS'; }
return 'INCORRECT';</answer>
</customhint>
<hintpart on="double">
<startouttext />
<p>
Egyptian Fractions cannot have the same denominator more than once. For example, 1/3+1/17+1/4+1/17 is not an Egyptian Fraction, as it has 17 twice as denominator.
</p>
<endouttext />
</hintpart>
</customresponse>
</problem>
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