--- /dev/null
+<html>
+<head>
+<title>Berechnete Fragen</title>
+</head>
+<body>
+<p align="center"><b>Berechnete Fragen</b></p>
+Calculated questions offers a way to create individual numerical
+question by the use of wildcards that are substituted with
+individual values when the quiz is taken.<br>
+Below is a shrunken view of the main editing page with some
+example inputs:<br>
+<table>
+<tbody>
+<tr valign="top">
+<td align="right">
+<p><b>Question:</b></p>
+</td>
+<td>
+<textarea id="questiontext" name="questiontext" rows="5" cols=
+"40" wrap="virtual">
+How much is {a} + {b} ?
+</textarea></td>
+</tr>
+<tr valign="top">
+<td align="right">
+<p><b>Image to display:</b></p>
+</td>
+<td><select name="image">
+<option value="" selected="selected">None</option>
+<option value="grevture.gif">grevture.gif</option>
+</select></td>
+</tr>
+<tr valign="top">
+<td align="right">
+<p><b>Correct Answer Formula:</b></p>
+</td>
+<td><input align="left" type="text" id="formula0" name="answer[]"
+size="20" value="{a} + {b}"> <input type="hidden" name=
+"fraction[]" value="1.0"></td>
+</tr>
+<tr valign="top">
+<td align="right">
+<p><b>Tolerance:</b></p>
+</td>
+<td><input align="left" type="text" id="tolerance0"" name=
+"tolerance[]" size="15" value="0.01">±</td>
+</tr>
+<tr valign="top">
+<td align="right">
+<p><b>Tolerance Type:</b></p>
+</td>
+<td><select name="tolerancetype[]">
+<option value="1" selected="selected">Relative</option>
+<option value="2">Nominal</option>
+<option value="3">Geometric</option>
+</select></td>
+</tr>
+<tr valign="top">
+<td align="right">
+<p><b>Significant Figures:</b></p>
+</td>
+<td><select name="correctanswerlength[]">
+<option value="1">1</option>
+<option value="2" selected="selected">2</option>
+<option value="3">3</option>
+<option value="4">4</option>
+<option value="5">5</option>
+<option value="6">6</option>
+<option value="7">7</option>
+<option value="8">8</option>
+<option value="9">9</option>
+<option value="10">10</option>
+</select></td>
+</tr>
+</tbody>
+</table>
+<br>
+In the question text input and "Correct Answer Formula" {a} and
+{b} can be seen. These and any other {name} can be used as a
+wildcard that is substituted by some value when the quiz is
+taken. Also, the correct answer is calculated when the quiz is
+submitted using the expression in "Correct Answer Formula", which
+is calculated as a numerical expression after the substitution of
+the wildcards. The possible wildcard values are set or generated
+on a later page in "editing wizard" for calculated
+questions...<br>
+The example formula uses the operator +. Other accepted operators
+are -*/ and % where % is the modulo operator. It is also possible
+to use some PHP-style mathematical function. Among these there
+are 24 single-argument function:<br>
+<b>abs, acos, acosh, asin, asinh, atan, atanh, ceil, cos, cosh,
+deg2rad, exp, expm1, floor, log, log10, log1p, rad2deg, round,
+sin, sinh, sprt, tan, tanh</b><br>
+and two two-argument functions<br>
+<b>atan2, pow</b><br>
+and the functions <b>min</b> and <b>max</b> that can take two or
+more arguments. It is also possible to use the function <b>pi</b>
+that takes no arguments but do not forget the use the parentheses
+- the correct usage is <b>pi()</b>. Similary the other function
+must have their argument(s) within parentheses. Possible usage is
+for example <b>sin({a}) + cos({b}) * 2</b>. It should not be any
+problem to wrap functions within eachother like
+<b>cos(deg2rad({a} + 90))</b> etc.<br>
+More details on how to use these PHP-style functions can be found
+in the <a target="phpmathdoc" href=
+"http://www.php.net/manual/en/ref.math.php">documentation at the
+PHP web site</a><br>
+<br>
+As for numerical questions it is possible to allow a margin
+within which all responses are accepted as correct. The
+"Tolerance" field is used for this. However, there are three
+different types of tolerances. These are <b>Relative, Nominal and
+Geometric</b>. If we say that the correct answer at quiz time is
+calculated to 200 and the tolerance is set to 0.5 then the
+different tolerance types work like this:<br>
+<br>
+<b>Relative:</b> A tolerance interval is calculated by
+multiplying the correct answer with 0.5, ie in this case we get
+100 so for this tolerance the correct response must be between
+100 and 300. (200 ± 100)<br>
+This is useful if the magnitude of the correct answer can differ
+greatly between different wildcard values.<br>
+<br>
+<b>Nominal:</b> This is the simpliest tolerance type but not very
+powerful. The correct response must be between 199.5 and 200.5
+(200 ± 0.5)<br>
+This tolerance type can be useful if the differences between
+different correct answers are small.<br>
+<br>
+<b>Geometric:</b> The upper limit of the tolerance interval is
+calculated as 200 + 0.5*200 and is the same as for the relative
+case. The lower limit is calculated as 200/(1 + 0.5). The correct
+response must then be between 133.33 and 300.<br>
+This is useful for complex calculation that must have great
+tolerances where relative tolerances of 1 or more would be used
+for the upper limit but clearly not acceptable for the lower
+limit as it would make zero a correct answer for all cases.<br>
+<br>
+The field <b>Significant Figures</b> does only relate to how the
+correct answer should be presented in the review or the reports.
+Examples: If it is set to 3 then the correct answer 13.333 would
+be presented as 13.3; 1236 would be presented as 1240; 23 would
+be presented as 23.0 etc.<br>
+<br>
+The feedback field and the optional unit fields work just like
+they do for numerical questions.<br>
+</body>
+</html>
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