question/format/gift/format.php

   1 <?php // $Id$
   2 //
   3 ///////////////////////////////////////////////////////////////
   4 // The GIFT import filter was designed as an easy to use method
   5 // for teachers writing questions as a text file. It supports most
   6 // question types and the missing word format.
   7 //
   8 // Multiple Choice / Missing Word
   9 //     Who's buried in Grant's tomb?{~Grant ~Jefferson =no one}
  10 //     Grant is {~buried =entombed ~living} in Grant's tomb.
  11 // True-False:
  12 //     Grant is buried in Grant's tomb.{FALSE}
  13 // Short-Answer.
  14 //     Who's buried in Grant's tomb?{=no one =nobody}
  15 // Numerical
  16 //     When was Ulysses S. Grant born?{#1822:5}
  17 // Matching
  18 //     Match the following countries with their corresponding
  19 //     capitals.{=Canada->Ottawa =Italy->Rome =Japan->Tokyo}
  20 //
  21 // Comment lines start with a double backslash (//).
  22 // Optional question names are enclosed in double colon(::).
  23 // Answer feedback is indicated with hash mark (#).
  24 // Percentage answer weights immediately follow the tilde (for
  25 // multiple choice) or equal sign (for short answer and numerical),
  26 // and are enclosed in percent signs (% %). See docs and examples.txt for more.
  27 //
  28 // This filter was written through the collaboration of numerous
  29 // members of the Moodle community. It was originally based on
  30 // the missingword format, which included code from Thomas Robb
  31 // and others. Paul Tsuchido Shew wrote this filter in December 2003.
  32 //////////////////////////////////////////////////////////////////////////
  33 // Based on default.php, included by ../import.php
  34 /**
  35  * @package questionbank
  36  * @subpackage importexport
  37  */
  38 class qformat_gift extends qformat_default {
  39
  40     function provide_import() {
  41         return true;
  42     }
  43
  44     function provide_export() {
  45         return true;
  46     }
  47
  48     function answerweightparser(&$answer) {
  49         $answer = substr($answer, 1);                        // removes initial %
  50         $end_position  = strpos($answer, "%");
  51         $answer_weight = substr($answer, 0, $end_position);  // gets weight as integer
  52         $answer_weight = $answer_weight/100;                 // converts to percent
  53         $answer = substr($answer, $end_position+1);          // removes comment from answer
  54         return $answer_weight;
  55     }
  56
  57
  58     function commentparser(&$answer) {
  59         if (strpos($answer,"#") > 0){
  60             $hashpos = strpos($answer,"#");
  61             $comment = substr($answer, $hashpos+1);
  62             $comment = addslashes(trim($this->escapedchar_post($comment)));
  63             $answer  = substr($answer, 0, $hashpos);
  64         } else {
  65             $comment = " ";
  66         }
  67         return $comment;
  68     }
  69
  70     function split_truefalse_comment($comment){
  71         // splits up comment around # marks
  72         // returns an array of true/false feedback
  73         $bits = explode('#',$comment);
  74         $feedback = array('wrong' => $bits[0]);
  75         if (count($bits) >= 2) {
  76             $feedback['right'] = $bits[1];
  77         } else {
  78             $feedback['right'] = '';
  79         }
  80         return $feedback;
  81     }
  82
  83     function escapedchar_pre($string) {
  84         //Replaces escaped control characters with a placeholder BEFORE processing
  85
  86         $escapedcharacters = array("\\:",    "\\#",    "\\=",    "\\{",    "\\}",    "\\~",    "\\n"   );  //dlnsk
  87         $placeholders      = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010" );  //dlnsk
  88
  89         $string = str_replace("\\\\", "&&092;", $string);
  90         $string = str_replace($escapedcharacters, $placeholders, $string);
  91         $string = str_replace("&&092;", "\\", $string);
  92         return $string;
  93     }
  94
  95     function escapedchar_post($string) {
  96         //Replaces placeholders with corresponding character AFTER processing is done
  97         $placeholders = array("&&058;", "&&035;", "&&061;", "&&123;", "&&125;", "&&126;", "&&010"); //dlnsk
  98         $characters   = array(":",     "#",      "=",      "{",      "}",      "~",      "\n"   ); //dlnsk
  99         $string = str_replace($placeholders, $characters, $string);
 100         return $string;
 101     }
 102
 103     function check_answer_count( $min, $answers, $text ) {
 104         $countanswers = count($answers);
 105         if ($countanswers < $min) {
 106             $importminerror = get_string( 'importminerror', 'quiz' );
 107             $this->error( $importminerror, $text );
 108             return false;
 109         }
 110
 111         return true;
 112     }
 113
 114
 115     function readquestion($lines) {
 116     // Given an array of lines known to define a question in this format, this function
 117     // converts it into a question object suitable for processing and insertion into Moodle.
 118
 119         $question = $this->defaultquestion();
 120         $comment = NULL;
 121         // define replaced by simple assignment, stop redefine notices
 122         $gift_answerweight_regex = "^%\-*([0-9]{1,2})\.?([0-9]*)%";
 123
 124         // REMOVED COMMENTED LINES and IMPLODE
 125         foreach ($lines as $key => $line) {
 126             $line = trim($line);
 127             if (substr($line, 0, 2) == "//") {
 128                 $lines[$key] = " ";
 129             }
 130         }
 131
 132         $text = trim(implode(" ", $lines));
 133
 134         if ($text == "") {
 135             return false;
 136         }
 137
 138         // Substitute escaped control characters with placeholders
 139         $text = $this->escapedchar_pre($text);
 140
 141         // Look for category modifier
 142         if (ereg( '^\$CATEGORY:', $text)) {
 143             // $newcategory = $matches[1];
 144             $newcategory = trim(substr( $text, 10 ));
 145
 146             // build fake question to contain category
 147             $question->qtype = 'category';
 148             $question->category = $newcategory;
 149             return $question;
 150         }
 151
 152         // QUESTION NAME parser
 153         if (substr($text, 0, 2) == "::") {
 154             $text = substr($text, 2);
 155
 156             $namefinish = strpos($text, "::");
 157             if ($namefinish === false) {
 158                 $question->name = false;
 159                 // name will be assigned after processing question text below
 160             } else {
 161                 $questionname = substr($text, 0, $namefinish);
 162                 $question->name = addslashes(trim($this->escapedchar_post($questionname)));
 163                 $text = trim(substr($text, $namefinish+2)); // Remove name from text
 164             }
 165         } else {
 166             $question->name = false;
 167         }
 168
 169
 170         // FIND ANSWER section
 171         // no answer means its a description
 172         $answerstart = strpos($text, "{");
 173         $answerfinish = strpos($text, "}");
 174
 175         $description = false;
 176         if (($answerstart === false) and ($answerfinish === false)) {
 177             $description = true;
 178             $answertext = '';
 179             $answerlength = 0;
 180         }
 181         elseif (!(($answerstart !== false) and ($answerfinish !== false))) {
 182             $this->error( get_string( 'braceerror', 'quiz' ), $text );
 183             return false;
 184         }
 185         else {
 186             $answerlength = $answerfinish - $answerstart;
 187             $answertext = trim(substr($text, $answerstart + 1, $answerlength - 1));
 188         }
 189
 190         // Format QUESTION TEXT without answer, inserting "_____" as necessary
 191         if ($description) {
 192             $questiontext = $text;
 193         }
 194         elseif (substr($text, -1) == "}") {
 195             // no blank line if answers follow question, outside of closing punctuation
 196             $questiontext = substr_replace($text, "", $answerstart, $answerlength+1);
 197         } else {
 198             // inserts blank line for missing word format
 199             $questiontext = substr_replace($text, "_____", $answerstart, $answerlength+1);
 200         }
 201
 202         // get questiontext format from questiontext
 203         $oldquestiontext = $questiontext;
 204         $questiontextformat = 0;
 205         if (substr($questiontext,0,1)=='[') {
 206             $questiontext = substr( $questiontext,1 );
 207             $rh_brace = strpos( $questiontext, ']' );
 208             $qtformat= substr( $questiontext, 0, $rh_brace );
 209             $questiontext = substr( $questiontext, $rh_brace+1 );
 210             if (!$questiontextformat = text_format_name( $qtformat )) {
 211                 $questiontext = $oldquestiontext;
 212             }
 213         }
 214         $question->questiontextformat = $questiontextformat;
 215         $question->questiontext = addslashes(trim($this->escapedchar_post($questiontext)));
 216
 217         // set question name if not already set
 218         if ($question->name === false) {
 219             $question->name = $question->questiontext;
 220             }
 221
 222         // ensure name is not longer than 250 characters
 223         $question->name = shorten_text( $question->name, 250 );
 224
 225         // determine QUESTION TYPE
 226         $question->qtype = NULL;
 227
 228         if ($description) {
 229             $question->qtype = DESCRIPTION;
 230         }
 231         elseif ($answertext == '') {
 232             $question->qtype = ESSAY;
 233         }
 234         elseif ($answertext{0} == "#"){
 235             $question->qtype = NUMERICAL;
 236
 237         } elseif (strpos($answertext, "~") !== false)  {
 238             // only Multiplechoice questions contain tilde ~
 239             $question->qtype = MULTICHOICE;
 240
 241         } elseif (strpos($answertext, "=")  !== false
 242                 && strpos($answertext, "->") !== false) {
 243             // only Matching contains both = and ->
 244             $question->qtype = MATCH;
 245
 246         } else { // either TRUEFALSE or SHORTANSWER
 247
 248             // TRUEFALSE question check
 249             $truefalse_check = $answertext;
 250             if (strpos($answertext,"#") > 0){
 251                 // strip comments to check for TrueFalse question
 252                 $truefalse_check = trim(substr($answertext, 0, strpos($answertext,"#")));
 253             }
 254
 255             $valid_tf_answers = array("T", "TRUE", "F", "FALSE");
 256             if (in_array($truefalse_check, $valid_tf_answers)) {
 257                 $question->qtype = TRUEFALSE;
 258
 259             } else { // Must be SHORTANSWER
 260                     $question->qtype = SHORTANSWER;
 261             }
 262         }
 263
 264         if (!isset($question->qtype)) {
 265             // try for plugins
 266             if ($question = $this->try_importing_using_qtypes( $lines, $question, $answertext )) {
 267                 return $question;
 268             }
 269             $giftqtypenotset = get_string('giftqtypenotset','quiz');
 270             $this->error( $giftqtypenotset, $text );
 271             return false;
 272         }
 273
 274         switch ($question->qtype) {
 275             case DESCRIPTION:
 276                 return $question;
 277                 break;
 278             case ESSAY:
 279                 $question->feedback = '';
 280                 $question->fraction = 0;
 281                 return $question;
 282                 break;
 283             case MULTICHOICE:
 284                 if (strpos($answertext,"=") === false) {
 285                     $question->single = 0;   // multiple answers are enabled if no single answer is 100% correct
 286                 } else {
 287                     $question->single = 1;   // only one answer allowed (the default)
 288                 }
 289
 290                 $answertext = str_replace("=", "~=", $answertext);
 291                 $answers = explode("~", $answertext);
 292                 if (isset($answers[0])) {
 293                     $answers[0] = trim($answers[0]);
 294                 }
 295                 if (empty($answers[0])) {
 296                     array_shift($answers);
 297                 }
 298
 299                 $countanswers = count($answers);
 300
 301                 if (!$this->check_answer_count( 2,$answers,$text )) {
 302                     return false;
 303                     break;
 304                 }
 305
 306                 foreach ($answers as $key => $answer) {
 307                     $answer = trim($answer);
 308
 309                     // determine answer weight
 310                     if ($answer[0] == "=") {
 311                         $answer_weight = 1;
 312                         $answer = substr($answer, 1);
 313
 314                     } elseif (ereg($gift_answerweight_regex, $answer)) {    // check for properly formatted answer weight
 315                         $answer_weight = $this->answerweightparser($answer);
 316
 317                     } else {     //default, i.e., wrong anwer
 318                         $answer_weight = 0;
 319                     }
 320                     $question->fraction[$key] = $answer_weight;
 321                     $question->feedback[$key] = $this->commentparser($answer); // commentparser also removes comment from $answer
 322                     $question->answer[$key]   = addslashes($this->escapedchar_post($answer));
 323                     $question->correctfeedback = '';
 324                     $question->partiallycorrectfeedback = '';
 325                     $question->incorrectfeedback = '';
 326                 }  // end foreach answer
 327
 328                 //$question->defaultgrade = 1;
 329                 //$question->image = "";   // No images with this format
 330                 return $question;
 331                 break;
 332
 333             case MATCH:
 334                 $answers = explode("=", $answertext);
 335                 if (isset($answers[0])) {
 336                     $answers[0] = trim($answers[0]);
 337                 }
 338                 if (empty($answers[0])) {
 339                     array_shift($answers);
 340                 }
 341
 342                 if (!$this->check_answer_count( 2,$answers,$text )) {
 343                     return false;
 344                     break;
 345                 }
 346
 347                 foreach ($answers as $key => $answer) {
 348                     $answer = trim($answer);
 349                     if (strpos($answer, "->") === false) {
 350                         $giftmatchingformat = get_string('giftmatchingformat','quiz');
 351                         $this->error($giftmatchingformat, $answer );
 352                         return false;
 353                         break 2;
 354                     }
 355
 356                     $marker = strpos($answer,"->");
 357                     $question->subquestions[$key] = addslashes(trim($this->escapedchar_post(substr($answer, 0, $marker))));
 358                     $question->subanswers[$key]   = addslashes(trim($this->escapedchar_post(substr($answer, $marker+2))));
 359
 360                 }  // end foreach answer
 361
 362                 return $question;
 363                 break;
 364
 365             case TRUEFALSE:
 366                 $answer = $answertext;
 367                 $comment = $this->commentparser($answer); // commentparser also removes comment from $answer
 368                 $feedback = $this->split_truefalse_comment($comment);
 369
 370                 if ($answer == "T" OR $answer == "TRUE") {
 371                     $question->answer = 1;
 372                     $question->feedbacktrue = $feedback['right'];
 373                     $question->feedbackfalse = $feedback['wrong'];
 374                 } else {
 375                     $question->answer = 0;
 376                     $question->feedbackfalse = $feedback['right'];
 377                     $question->feedbacktrue = $feedback['wrong'];
 378                 }
 379
 380                 $question->correctanswer = $question->answer;
 381
 382                 return $question;
 383                 break;
 384
 385             case SHORTANSWER:
 386                 // SHORTANSWER Question
 387                 $answers = explode("=", $answertext);
 388                 if (isset($answers[0])) {
 389                     $answers[0] = trim($answers[0]);
 390                 }
 391                 if (empty($answers[0])) {
 392                     array_shift($answers);
 393                 }
 394
 395                 if (!$this->check_answer_count( 1,$answers,$text )) {
 396                     return false;
 397                     break;
 398                 }
 399
 400                 foreach ($answers as $key => $answer) {
 401                     $answer = trim($answer);
 402
 403                     // Answer Weight
 404                     if (ereg($gift_answerweight_regex, $answer)) {    // check for properly formatted answer weight
 405                         $answer_weight = $this->answerweightparser($answer);
 406                     } else {     //default, i.e., full-credit anwer
 407                         $answer_weight = 1;
 408                     }
 409                     $question->fraction[$key] = $answer_weight;
 410                     $question->feedback[$key] = $this->commentparser($answer); //commentparser also removes comment from $answer
 411                     $question->answer[$key]   = addslashes($this->escapedchar_post($answer));
 412                 }     // end foreach
 413
 414                 //$question->usecase = 0;  // Ignore case
 415                 //$question->defaultgrade = 1;
 416                 //$question->image = "";   // No images with this format
 417                 return $question;
 418                 break;
 419
 420             case NUMERICAL:
 421                 // Note similarities to ShortAnswer
 422                 $answertext = substr($answertext, 1); // remove leading "#"
 423
 424                 // If there is feedback for a wrong answer, store it for now.
 425                 if (($pos = strpos($answertext, '~')) !== false) {
 426                     $wrongfeedback = substr($answertext, $pos);
 427                     $answertext = substr($answertext, 0, $pos);
 428                 } else {
 429                     $wrongfeedback = '';
 430                 }
 431
 432                 $answers = explode("=", $answertext);
 433                 if (isset($answers[0])) {
 434                     $answers[0] = trim($answers[0]);
 435                 }
 436                 if (empty($answers[0])) {
 437                     array_shift($answers);
 438                 }
 439
 440                 if (count($answers) == 0) {
 441                     // invalid question
 442                     $giftnonumericalanswers = get_string('giftnonumericalanswers','quiz');
 443                     $this->error( $giftnonumericalanswers, $text );
 444                     return false;
 445                     break;
 446                 }
 447
 448                 foreach ($answers as $key => $answer) {
 449                     $answer = trim($answer);
 450
 451                     // Answer weight
 452                     if (ereg($gift_answerweight_regex, $answer)) {    // check for properly formatted answer weight
 453                         $answer_weight = $this->answerweightparser($answer);
 454                     } else {     //default, i.e., full-credit anwer
 455                         $answer_weight = 1;
 456                     }
 457                     $question->fraction[$key] = $answer_weight;
 458                     $question->feedback[$key] = $this->commentparser($answer); //commentparser also removes comment from $answer
 459
 460                     //Calculate Answer and Min/Max values
 461                     if (strpos($answer,"..") > 0) { // optional [min]..[max] format
 462                         $marker = strpos($answer,"..");
 463                         $max = trim(substr($answer, $marker+2));
 464                         $min = trim(substr($answer, 0, $marker));
 465                         $ans = ($max + $min)/2;
 466                         $tol = $max - $ans;
 467                     } elseif (strpos($answer,":") > 0){ // standard [answer]:[errormargin] format
 468                         $marker = strpos($answer,":");
 469                         $tol = trim(substr($answer, $marker+1));
 470                         $ans = trim(substr($answer, 0, $marker));
 471                     } else { // only one valid answer (zero errormargin)
 472                         $tol = 0;
 473                         $ans = trim($answer);
 474                     }
 475
 476                     if (!(is_numeric($ans) || $ans = '*') || !is_numeric($tol)) {
 477                             $errornotnumbers = get_string( 'errornotnumbers' );
 478                             $this->error( $errornotnumbers, $text );
 479                         return false;
 480                         break;
 481                     }
 482
 483                     // store results
 484                     $question->answer[$key] = $ans;
 485                     $question->tolerance[$key] = $tol;
 486                 } // end foreach
 487
 488                 if ($wrongfeedback) {
 489                     $key += 1;
 490                     $question->fraction[$key] = 0;
 491                     $question->feedback[$key] = $this->commentparser($wrongfeedback);
 492                     $question->answer[$key] = '';
 493                     $question->tolerance[$key] = '';
 494                 }
 495
 496                 return $question;
 497                 break;
 498
 499                 default:
 500                     $giftnovalidquestion = get_string('giftnovalidquestion','quiz');
 501                     $this->error( $giftnovalidquestion, $text );
 502                 return false;
 503                 break;
 504
 505         } // end switch ($question->qtype)
 506
 507     }    // end function readquestion($lines)
 508
 509 function repchar( $text, $format=0 ) {
 510     // escapes 'reserved' characters # = ~ { ) : and removes new lines
 511     // also pushes text through format routine
 512     $reserved = array( '#', '=', '~', '{', '}', ':', "\n","\r");
 513     $escaped =  array( '\#','\=','\~','\{','\}','\:','\n',''  ); //dlnsk
 514
 515     $newtext = str_replace( $reserved, $escaped, $text );
 516     $format = 0; // turn this off for now
 517     if ($format) {
 518         $newtext = format_text( $format );
 519     }
 520     return $newtext;
 521     }
 522
 523 function writequestion( $question ) {
 524     // turns question into string
 525     // question reflects database fields for general question and specific to type
 526
 527     // initial string;
 528     $expout = "";
 529
 530     // add comment
 531     $expout .= "// question: $question->id  name: $question->name \n";
 532
 533     // get  question text format
 534     $textformat = $question->questiontextformat;
 535     $tfname = "";
 536     if ($textformat!=FORMAT_MOODLE) {
 537         $tfname = text_format_name( (int)$textformat );
 538         $tfname = "[$tfname]";
 539     }
 540
 541     // output depends on question type
 542     switch($question->qtype) {
 543     case 'category':
 544         // not a real question, used to insert category switch
 545         $expout .= "\$CATEGORY: $question->category\n";
 546         break;
 547     case DESCRIPTION:
 548         $expout .= '::'.$this->repchar($question->name).'::';
 549         $expout .= $tfname;
 550         $expout .= $this->repchar( $question->questiontext, $textformat);
 551         break;
 552     case ESSAY:
 553         $expout .= '::'.$this->repchar($question->name).'::';
 554         $expout .= $tfname;
 555         $expout .= $this->repchar( $question->questiontext, $textformat);
 556         $expout .= "{}\n";
 557         break;
 558     case TRUEFALSE:
 559         $trueanswer = $question->options->answers[$question->options->trueanswer];
 560         $falseanswer = $question->options->answers[$question->options->falseanswer];
 561         if ($trueanswer->fraction == 1) {
 562             $answertext = 'TRUE';
 563             $right_feedback = $trueanswer->feedback;
 564             $wrong_feedback = $falseanswer->feedback;
 565         } else {
 566             $answertext = 'FALSE';
 567             $right_feedback = $falseanswer->feedback;
 568             $wrong_feedback = $trueanswer->feedback;
 569         }
 570
 571         $wrong_feedback = $this->repchar($wrong_feedback);
 572         $right_feedback = $this->repchar($right_feedback);
 573         $expout .= "::".$this->repchar($question->name)."::".$tfname.$this->repchar( $question->questiontext,$textformat )."{".$this->repchar( $answertext );
 574         if ($wrong_feedback) {
 575             $expout .= "#" . $wrong_feedback;
 576         } else if ($right_feedback) {
 577             $expout .= "#";
 578         }
 579         if ($right_feedback) {
 580             $expout .= "#" . $right_feedback;
 581         }
 582         $expout .= "}\n";
 583         break;
 584     case MULTICHOICE:
 585         $expout .= "::".$this->repchar($question->name)."::".$tfname.$this->repchar( $question->questiontext, $textformat )."{\n";
 586         foreach($question->options->answers as $answer) {
 587             if ($answer->fraction==1) {
 588                 $answertext = '=';
 589             }
 590             elseif ($answer->fraction==0) {
 591                 $answertext = '~';
 592             }
 593             else {
 594                 $export_weight = $answer->fraction*100;
 595                 $answertext = "~%$export_weight%";
 596             }
 597             $expout .= "\t".$answertext.$this->repchar( $answer->answer );
 598             if ($answer->feedback!="") {
 599                 $expout .= "#".$this->repchar( $answer->feedback );
 600             }
 601             $expout .= "\n";
 602         }
 603         $expout .= "}\n";
 604         break;
 605     case SHORTANSWER:
 606         $expout .= "::".$this->repchar($question->name)."::".$tfname.$this->repchar( $question->questiontext, $textformat )."{\n";
 607         foreach($question->options->answers as $answer) {
 608             $weight = 100 * $answer->fraction;
 609             $expout .= "\t=%".$weight."%".$this->repchar( $answer->answer )."#".$this->repchar( $answer->feedback )."\n";
 610         }
 611         $expout .= "}\n";
 612         break;
 613     case NUMERICAL:
 614         $expout .= "::".$this->repchar($question->name)."::".$tfname.$this->repchar( $question->questiontext, $textformat )."{#\n";
 615         foreach ($question->options->answers as $answer) {
 616             if ($answer->answer != '') {
 617                 $expout .= "\t=".$answer->answer.":".(float)$answer->tolerance."#".$this->repchar( $answer->feedback )."\n";
 618             } else {
 619                 $expout .= "\t~#".$this->repchar( $answer->feedback )."\n";
 620             }
 621         }
 622         $expout .= "}\n";
 623         break;
 624     case MATCH:
 625         $expout .= "::".$this->repchar($question->name)."::".$tfname.$this->repchar( $question->questiontext, $textformat )."{\n";
 626         foreach($question->options->subquestions as $subquestion) {
 627             $expout .= "\t=".$this->repchar( $subquestion->questiontext )." -> ".$this->repchar( $subquestion->answertext )."\n";
 628         }
 629         $expout .= "}\n";
 630         break;
 631     case DESCRIPTION:
 632         $expout .= "// DESCRIPTION type is not supported\n";
 633         break;
 634     case MULTIANSWER:
 635         $expout .= "// CLOZE type is not supported\n";
 636         break;
 637     default:
 638         // check for plugins
 639         if ($out = $this->try_exporting_using_qtypes( $question->qtype, $question )) {
 640             $expout .= $out;
 641         }
 642         else {
 643             notify("No handler for qtype '$question->qtype' for GIFT export" );
 644         }
 645     }
 646     // add empty line to delimit questions
 647     $expout .= "\n";
 648     return $expout;
 649 }
 650 }
 651 ?>