Details
Sub-task
Closed
Minor
Description
When the answer is a small number i.e 1e-19 as the charge of the electron the range of the allowed answer can extend to negative value given the fact that the code of add +- a small number
line 355 of numerical/questiontype.php in the function get_tolerance_interval(&$answer) {
// We need to add a tiny fraction depending on the set precision to make the
// comparison work correctly. Otherwise seemingly equal values can yield
// false. (fixes bug #3225)
$tolerance = (float)$answer->tolerance + ("1.0e-".ini_get('precision'));
This is to remediate for the 0.000000001 or .999999999 possible output of real number functions.
So if the user put an answer like 1.6e-5 php code could sometimes see it 0.0000159999999 or 0.00001600000001
for small answer values the tiny fraction should be calcualted as a fraction of the number and not an absolute value
actually ("1.0e-".ini_get('precision')); can gives something like 1e-13 for a precision of 8 .
After completing tests, a working solution will be proposed soon
Issue Links
- is duplicated by
-
MDL-12375
Improving the grading of calculated question when there numbers are near the testing limit
-
Modifying the line 360 and followings of numerical/questiontype.php to
{ $tolerance = 0.01* abs((float)$answer->answer) ; //arbitrary factor 1.01 }switch ($answer->tolerancetype) {
case '1': case 'relative':
/// Recalculate the tolerance and fall through
/// to the nominal case:
$tolerance = $answer->answer * $tolerance;
// Do not fall through to the nominal case because the tiny fraction is a factor of the answer
$tolerance = abs($tolerance); // important - otherwise min and max are swapped
$max = $answer->answer + $tolerance;
$min = $answer->answer - $tolerance;
break;
case '2': case 'nominal':
$tolerance = abs($tolerance); // important - otherwise min and max are swapped
// $answer->tolerance 0 or something else
if ((float)$answer->tolerance == 0.0 && abs((float)$answer->answer) <= $tolerance )
else if ((float)$answer->tolerance != 0.0 && abs((float)$answer->tolerance) < abs((float)$answer->answer) && abs((float)$answer->answer) <= $tolerance)
{ $tolerance = 1.01 * abs((float) $answer->tolerance) ;//arbitrary factor 1.01 }$max = $answer->answer + $tolerance;
$min = $answer->answer - $tolerance;
break;
solve the problem
More complete report on testing done will follow on moodle docs and or quiz forum.