diff options
Diffstat (limited to 'question.php')
| -rw-r--r-- | question.php | 178 |
1 files changed, 88 insertions, 90 deletions
diff --git a/question.php b/question.php index e9dffcf..ab024a7 100644 --- a/question.php +++ b/question.php @@ -77,98 +77,98 @@ class qtype_algebra_question extends question_graded_by_strategy return get_string('pleaseenterananswer', 'qtype_algebra'); } - /** - * Parses the given expression with the parser if required. - * - * This method will check to see if the argument it is given is already a parsed - * expression and if not will attempt to parse it. - * - * @param $expr expression which will be parsed - * @return top term of the parse tree or a string if an exception is thrown - */ + /** + * Parses the given expression with the parser if required. + * + * This method will check to see if the argument it is given is already a parsed + * expression and if not will attempt to parse it. + * + * @param $expr expression which will be parsed + * @return top term of the parse tree or a string if an exception is thrown + */ public function parse_expression($expr) { - // Check to see if this is already a parsed expression - if(is_a($expr,'qtype_algebra_parser_term')) { - // It is a parsed expression so simply return it + // Check to see if this is already a parsed expression. + if (is_a($expr, 'qtype_algebra_parser_term')) { + // It is a parsed expression so simply return it. return $expr; } - // Create an array of variable names for the parser from the question if defined + // Create an array of variable names for the parser from the question if defined. $varnames=array(); - if(isset($this->variables)) { - foreach($this->variables as $var) { + if (isset($this->variables)) { + foreach ($this->variables as $var) { $varnames[]=$var->name; } } // We now assume that we have a string to parse. Create a parser instance to - // to this and return the parser expression at the top of the parse tree + // to this and return the parser expression at the top of the parse tree. $p=new qtype_algebra_parser; // Perform the actual parsing inside a try-catch block so that any exceptions - // can be caught and converted into errors + // can be caught and converted into errors. try { - return $p->parse($expr,$varnames); - } catch(Exception $e) { + return $p->parse($expr, $varnames); + } catch (Exception $e) { // If the expression cannot be parsed then return a null term. This will // make Moodle treat the answer as wrong. // TODO: Would be nice to have support for 'invalid answer' in the quiz - // engine since an unparseable response is usually caused by a silly typo + // engine since an unparseable response is usually caused by a silly typo. return new qtype_algebra_parser_nullterm; } } - /** - * Parses the given expression with the parser if required. - * - * This method will parse the expression and return a TeX string - * or empty string - * - * @param $expr expression which will be parsed - * @return top term of the parse tree or a string if an exception is thrown - */ + /** + * Parses the given expression with the parser if required. + * + * This method will parse the expression and return a TeX string + * or empty string + * + * @param $expr expression which will be parsed + * @return top term of the parse tree or a string if an exception is thrown + */ public function formated_expression($text) { - // Create an array of variable names for the parser from the question if defined + // Create an array of variable names for the parser from the question if defined. $varnames=array(); - if(isset($this->variables)) { - foreach($this->variables as $var) { + if (isset($this->variables)) { + foreach ($this->variables as $var) { $varnames[]=$var->name; } } // We now assume that we have a string to parse. Create a parser instance to - // to this and return the parser expression at the top of the parse tree + // to this and return the parser expression at the top of the parse tree. $p=new qtype_algebra_parser; // Perform the actual parsing inside a try-catch block so that any exceptions - // can be caught and converted into errors + // can be caught and converted into errors. try { $exp = $p->parse($text, $varnames); return '$$'.$exp->tex().'$$'; - } catch(Exception $e) { + } catch (Exception $e) { return ''; } } public function is_same_response(array $prevresponse, array $newresponse) { - // Check that both states have valid responses + // Check that both states have valid responses. if (!isset($prevresponse['answer']) or !isset($newresponse['answer'])) { - // At last one of the states did not have a response set so return false by default + // At last one of the states did not have a response set so return false by default. return false; } - // Parse the previous response + // Parse the previous response. $expr=$this->parse_expression($prevresponse['answer']); - // Parse the new response + // Parse the new response. $testexpr=$this->parse_expression($newresponse['answer']); // The type of comparison done depends on the comparision algorithm selected by // the question. Use the defined algorithm to select which comparison function // to call... - if($this->compareby == 'sage') { - // Uses an XML-RPC server with SAGE to perform a full symbollic comparision - return self::test_response_by_sage($expr,$testexpr); - } else if($this->compareby == 'eval') { - // Tests the response by evaluating it for a certain range of each variable - return self::test_response_by_evaluation($expr,$testexpr); + if ($this->compareby == 'sage') { + // Uses an XML-RPC server with SAGE to perform a full symbollic comparision. + return self::test_response_by_sage($expr, $testexpr); + } else if ($this->compareby == 'eval') { + // Tests the response by evaluating it for a certain range of each variable. + return self::test_response_by_evaluation($expr, $testexpr); } else { - // Tests the response by performing a simple parse tree equivalence algorithm - return self::test_response_by_equivalence($expr,$testexpr); + // Tests the response by performing a simple parse tree equivalence algorithm. + return self::test_response_by_equivalence($expr, $testexpr); } } @@ -177,31 +177,31 @@ class qtype_algebra_question extends question_graded_by_strategy } public function compare_response_with_answer(array $response, question_answer $answer) { - // Deal with the match anything answer by returning true + // Deal with the match anything answer by returning true. if ($answer->answer == '*') { return true; } $expr=$this->parse_expression($response['answer']); // Check that there is a response and if not return false. We do this here // because even an empty response should match a widlcard answer. - if(is_a($expr,'qtype_algebra_parser_nullterm')) { + if (is_a($expr, 'qtype_algebra_parser_nullterm')) { return false; } - // Now parse the answer + // Now parse the answer. $ansexpr=$this->parse_expression($answer->answer); // The type of comparison done depends on the comparision algorithm selected by // the question. Use the defined algorithm to select which comparison function // to call... - if($this->compareby == 'sage') { - // Uses an XML-RPC server with SAGE to perform a full symbollic comparision - return self::test_response_by_sage($expr,$ansexpr); - } else if($this->compareby == 'eval') { - // Tests the response by evaluating it for a certain range of each variable - return self::test_response_by_evaluation($expr,$ansexpr); + if ($this->compareby == 'sage') { + // Uses an XML-RPC server with SAGE to perform a full symbollic comparision. + return self::test_response_by_sage($expr, $ansexpr); + } else if ($this->compareby == 'eval') { + // Tests the response by evaluating it for a certain range of each variable. + return self::test_response_by_evaluation($expr, $ansexpr); } else { - // Tests the response by performing a simple parse tree equivalence algorithm - return self::test_response_by_equivalence($expr,$ansexpr); + // Tests the response by performing a simple parse tree equivalence algorithm. + return self::test_response_by_equivalence($expr, $ansexpr); } } @@ -215,20 +215,20 @@ class qtype_algebra_question extends question_graded_by_strategy * * @return boolean true if the response matches the answer, false otherwise */ - function test_response_by_sage($response, $answer) { + public function test_response_by_sage($response, $answer) { $request=array( 'host' => $CFG->qtype_algebra_host, 'port' => $CFG->qtype_algebra_port, 'uri' => $CFG->qtype_algebra_uri, ); - // Sets the name of the method to call to full_symbolic_compare + // Sets the name of the method to call to full_symbolic_compare. $request['method']='full_symbolic_compare'; - // Get a list of all the variables to declare + // Get a list of all the variables to declare. $vars=$response->get_variables(); - $vars=array_merge($vars,array_diff($vars,$answer->get_variables())); - // Sets the arguments to the sage string of the response and the list of variables - $request['args']=array($answer->sage(),$response->sage(),$vars); - // Calls the XML-RPC method on the server and returns the response + $vars=array_merge($vars, array_diff($vars, $answer->get_variables())); + // Sets the arguments to the sage string of the response and the list of variables. + $request['args']=array($answer->sage(), $response->sage(), $vars); + // Calls the XML-RPC method on the server and returns the response. return xu_rpc_http_concise($request)==0; } @@ -242,46 +242,44 @@ class qtype_algebra_question extends question_graded_by_strategy * * @return boolean true if the response matches the answer, false otherwise */ - function test_response_by_evaluation($response, $answer) { - // Flag used to denote mismatch in response and answer + public function test_response_by_evaluation($response, $answer) { + // Flag used to denote mismatch in response and answer. $same=true; // Run the evaluation loop 10 times with different random variables... - for($i=0;$i<$this->nchecks;$i++) { - // Create an array to store the values of all the variables + for ($i=0; $i<$this->nchecks; $i++) { + // Create an array to store the values of all the variables. $values=array(); - // Loop over all the variables in the question - foreach($this->variables as $var) { - // Set the value of the variable to a random number between the min and max + // Loop over all the variables in the question. + foreach ($this->variables as $var) { + // Set the value of the variable to a random number between the min and max. $values[$var->name]=$var->min+lcg_value()*abs($var->max-$var->min); } $resp_value=$response->evaluate($values); $ans_value=$answer->evaluate($values); - // Return false if only one of the reponse or answer gives NaN - if(is_nan($resp_value) xor is_nan($ans_value)) { + // Return false if only one of the reponse or answer gives NaN. + if (is_nan($resp_value) xor is_nan($ans_value)) { return false; } - // Return false if only one of the reponse or answer is infinite - if(is_infinite($resp_value) xor is_infinite($ans_value)) { + // Return false if only one of the reponse or answer is infinite. + if (is_infinite($resp_value) xor is_infinite($ans_value)) { return false; } // Use the fractional difference method if the answer has a value - // which is clearly distinguishable from zero - if(abs($ans_value)>1e-300) { - // Get the difference between the response and answer evaluations + // which is clearly distinguishable from zero. + if (abs($ans_value)>1e-300) { + // Get the difference between the response and answer evaluations. $diff=abs(($resp_value-$ans_value)/$ans_value); - } - // Otherwise use an arbitrary minimum value - else { - // Get the difference between the response and answer evaluations + } else { + // Otherwise use an arbitrary minimum value. $diff=abs(($resp_value-$ans_value)/1e-300); } - // Check to see if the difference is greater than tolerance - if($diff > $this->tolerance) { - // Return false since the formulae have been shown not to be the same + // Check to see if the difference is greater than tolerance. + if ($diff > $this->tolerance) { + // Return false since the formulae have been shown not to be the same. return false; } } - // We made it through the loop so now return true + // We made it through the loop so now return true. return true; } @@ -296,7 +294,7 @@ class qtype_algebra_question extends question_graded_by_strategy * @return boolean true if the response matches the answer, false otherwise */ public function test_response_by_equivalence($response, $answer) { - // Use the parser's equivalent method to see if the response is the same as the answer + // Use the parser's equivalent method to see if the response is the same as the answer. return $response->equivalent($answer); } @@ -304,8 +302,8 @@ class qtype_algebra_question extends question_graded_by_strategy $args, $forcedownload) { if ($component == 'question' && $filearea == 'answerfeedback') { $currentanswer = $qa->get_last_qt_var('answer'); - $answer = $qa->get_question()->get_matching_answer(array('answer' => $currentanswer)); - $answerid = reset($args); // itemid is answer id. + $answer = $this->get_matching_answer(array('answer' => $currentanswer)); + $answerid = reset($args); // Parameter itemid is answer id. return $options->feedback && $answerid == $answer->id; } else if ($component == 'question' && $filearea == 'hint') { |