File:  [LON-CAPA] / loncom / homework / default_homework.lcpm
Revision 1.142: download - view: text, annotated - select for diffs
Wed Nov 26 18:11:52 2008 UTC (15 years, 5 months ago) by raeburn
Branches: MAIN
CVS tags: version_2_8_0, version_2_7_99_1, version_2_7_99_0, HEAD
Formularesponse will not accept a comma in an individual submission  - either as a scalar answer or within a single component in a vector answer (for vectors: components are split on , prior to this evaluation phase).

    1: # The LearningOnline Network with CAPA 
    2: # used by lonxml::xmlparse() as input variable $safeinit to Apache::run::run()
    3: #
    4: # $Id: default_homework.lcpm,v 1.142 2008/11/26 18:11:52 raeburn Exp $
    5: #
    6: # Copyright Michigan State University Board of Trustees
    7: #
    8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
    9: #
   10: # LON-CAPA is free software; you can redistribute it and/or modify
   11: # it under the terms of the GNU General Public License as published by
   12: # the Free Software Foundation; either version 2 of the License, or
   13: # (at your option) any later version.
   14: #
   15: # LON-CAPA is distributed in the hope that it will be useful,
   16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   18: # GNU General Public License for more details.
   19: #
   20: # You should have received a copy of the GNU General Public License
   21: # along with LON-CAPA; if not, write to the Free Software
   22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   23: #
   24: # /home/httpd/html/adm/gpl.txt
   25: #
   26: # http://www.lon-capa.org/
   27: #
   28: #
   29: 
   30: #init some globals
   31: $hidden::RANDOMINIT=0;
   32: $pi=atan2(1,1)*4;
   33: $rad2deg=180.0/$pi;
   34: $deg2rad=$pi/180.0;
   35: $"=' ';
   36: use strict;
   37: {
   38:     my $n = 0;
   39:     my $total = 0;
   40:     my $num_left = 0;
   41:     my @order;
   42:     my $type;
   43: 
   44:     sub init_permutation {
   45: 	my ($size,$requested_type) = @_;
   46: 	@order = (0..$size-1);
   47: 	$n = $size;
   48: 	$type = $requested_type;
   49: 	if ($type eq 'ordered') {
   50: 	    $total = $num_left = 1;
   51: 	} elsif ($type eq 'unordered') {
   52: 	    $total = $num_left = &factorial($size);
   53: 	} else {
   54: 	    die("Unkown type: $type");
   55: 	}
   56:     }
   57: 
   58:     sub get_next_permutation {
   59: 	if ($num_left == $total) {
   60: 	    $num_left--;
   61: 	    return \@order;
   62: 	}
   63: 
   64: 	# Find largest index j with a[j] < a[j+1]
   65: 
   66: 	my $j = scalar(@order) - 2;
   67: 	while ($order[$j] > $order[$j+1]) {
   68: 	    $j--;
   69: 	}
   70: 
   71: 	# Find index k such that a[k] is smallest integer
   72: 	# greater than a[j] to the right of a[j]
   73: 
   74: 	my $k = scalar(@order) - 1;
   75: 	while ($order[$j] > $order[$k]) {
   76: 	    $k--;
   77: 	}
   78: 
   79: 	# Interchange a[j] and a[k]
   80: 
   81: 	@order[($k,$j)] = @order[($j,$k)];
   82: 
   83: 	# Put tail end of permutation after jth position in increasing order
   84: 
   85: 	my $r = scalar(@order) - 1;
   86: 	my $s = $j + 1;
   87: 
   88: 	while ($r > $s) {
   89: 	    @order[($s,$r)]=@order[($r,$s)];
   90: 	    $r--;
   91: 	    $s++;
   92: 	}
   93: 
   94: 	$num_left--;
   95: 	return(\@order);
   96:     }
   97:     
   98:     sub get_permutations_left {
   99: 	return $num_left;
  100:     }
  101: }
  102: 
  103: sub check_commas {
  104:     my ($response)=@_;
  105:     #print("$response ");
  106:     my @numbers=split(',',$response);
  107:     #print(" numbers ".join('-',@numbers)." ");
  108:     if (scalar(@numbers) > 1) {
  109:         #print(" numbers[0] ".$numbers[0]." "); 
  110: 	if (length($numbers[0]) > 3 || length($numbers[0]) == 0) { return -1; }
  111: 	shift(@numbers);
  112: 	#print(" numbers ".scalar(@numbers)." ");
  113: 	while (scalar(@numbers) > 1) {
  114: 	    #print(" numbers ".join('-',@numbers)." ");
  115: 	    if (length($numbers[0]) != 3) { return -2; }
  116: 	    shift(@numbers);
  117: 	}
  118: 	my ($number)=split('\.',$numbers[0]);
  119: 	#print(" number ".$number." ");
  120: 	#print(" numbers[0] ".$numbers[0]." ");
  121: 	if (length($number) != 3) { return -3; }
  122:     } else {
  123: 	my ($number)=split('\.',$numbers[0]);
  124: 	if (length($number) > 3) { return -4; }
  125:     }
  126:     return 1;
  127: }
  128: 
  129: 
  130: sub caparesponse_check {
  131:     my ($answer,$response)=@_;
  132:     #not properly used yet: calc
  133:     #not to be used: $ans_fmt
  134:     my $type=$LONCAPA::CAPAresponse_args{'type'};
  135:     my $tol=$LONCAPA::CAPAresponse_args{'tol'};
  136:     my $sig=$LONCAPA::CAPAresponse_args{'sig'};
  137:     my $ans_fmt=$LONCAPA::CAPAresponse_args{'format'};
  138:     my $unit=$LONCAPA::CAPAresponse_args{'unit'};
  139:     my $calc=$LONCAPA::CAPAresponse_args{'calc'};
  140:     my $samples=$LONCAPA::CAPAresponse_args{'samples'};
  141:     
  142:     my $tol_type=''; # gets it's value from whether tol has a % or not done
  143:     my $sig_lbound=''; #done
  144:     my $sig_ubound=''; #done
  145: 
  146: 
  147:     #type's definitons come from capaParser.h
  148: 
  149:     #remove leading and trailing whitespace
  150:     if (!defined($response)) {
  151: 	$response='';
  152:     }
  153:     if ($response=~ /^\s|\s$/) {
  154: 	$response=~ s:^\s+|\s+$::g;
  155: 	&LONCAPA_INTERNAL_DEBUG("Removed ws now :$response:");
  156:     }
  157: 
  158:     #&LONCAPA_INTERNAL_DEBUG(" type is $type ");
  159:     if ($type eq 'cs' || $type eq 'ci') {
  160: 	#for string answers make sure all places spaces occur, there is 
  161:         #really only 1 space, in both the answer and the response
  162: 	$answer=~s/ +/ /g;
  163: 	$response=~s/ +/ /g;
  164:     } elsif ($type eq 'mc') {
  165: 	$answer=~s/[\s,]//g;
  166: 	$response=~s/[\s,]//g;
  167:     }
  168:     if ($type eq 'float' && $unit=~/\$/) {
  169: 	if ($response!~/^\$|\$$/)  { return ('NO_UNIT', undef); }
  170: 	$response=~s/\$//g;
  171:     }
  172:     if ($type eq 'float' && $unit=~/\,/ && (&check_commas($response)<0)) {
  173: 	return "COMMA_FAIL:";
  174:     }
  175:     $ans_fmt=~s/\W//g;
  176:     $unit=~s/[\$,]//g;
  177:     if ($type eq 'float') { $response=~s/,//g; }
  178: 
  179:     if (length($response) > 500) { return ('TOO_LONG',undef); }
  180: 
  181:     if ($type eq '' ) {
  182: 	&LONCAPA_INTERNAL_DEBUG("Didn't find a type :$type: defaulting");
  183: 	if ( $answer eq ($answer *1.0)) { $type = 2;
  184: 				      } else { $type = 3; }
  185:     } else {
  186: 	if    ($type eq 'cs')    { $type = 4; }
  187: 	elsif ($type eq 'ci')    { $type = 3 }
  188: 	elsif ($type eq 'mc')    { $type = 5; }
  189: 	elsif ($type eq 'fml')   { $type = 8; }
  190:         elsif ($type eq 'math')  { $type = 9; }
  191: 	elsif ($type eq 'subj')  { $type = 7; }
  192: 	elsif ($type eq 'float') { $type = 2; }
  193: 	elsif ($type eq 'int')   { $type = 1; }
  194: 	else { return ('ERROR', "Unknown type of answer: $type") }
  195:     }
  196: 
  197:     my $points;
  198:     my $id_list;
  199:     #formula type setup the sample points
  200:     if ($type eq '8') {
  201: 	($id_list,$points)=split(/@/,$samples);
  202: 	&LONCAPA_INTERNAL_DEBUG("Found :$id_list:$points: points in $samples");
  203:     }
  204:     if ($tol eq '') {
  205: 	$tol=0.0;
  206: 	$tol_type=1; #TOL_ABSOLUTE
  207:     } else {
  208: 	if ($tol =~ /%$/) {
  209: 	    chop $tol;
  210: 	    $tol_type=2; #TOL_PERCENTAGE
  211: 	} else {
  212: 	    $tol_type=1; #TOL_ABSOLUTE
  213: 	}
  214:     }
  215: 
  216:     ($sig_ubound,$sig_lbound)=&LONCAPA_INTERNAL_get_sigrange($sig);
  217: 
  218:     my $reterror="";
  219:     my $result;
  220:     if (($type eq '9') || ($type eq '8')) {
  221:         if ($response=~/\=/) {
  222:             return ('BAD_FORMULA','Please submit just an expression, not an equation.');
  223:         } elsif ($response =~ /\,/) {
  224:             return ('BAD_FORMULA');
  225:         }
  226:     }
  227:     if ($type eq '9') {
  228:       $result = &maxima_check(&maxima_cas_formula_fix($response),&maxima_cas_formula_fix($answer),\$reterror);
  229:     } else {
  230: 	if ($type eq '8') { # fml type
  231: 	    $response = &capa_formula_fix($response);
  232: 	    $answer   = &capa_formula_fix($answer);
  233: 	}
  234:        $result = &caparesponse_capa_check_answer($response,$answer,$type,
  235: 						 $tol_type,$tol,
  236: 						 $sig_lbound,$sig_ubound,
  237: 						 $ans_fmt,$unit,$calc,$id_list,
  238: 						 $points,$external::randomseed,
  239: 						 \$reterror);
  240:     }
  241:     if    ($result == '1') { $result='EXACT_ANS'; } 
  242:     elsif ($result == '2') { $result='APPROX_ANS'; }
  243:     elsif ($result == '3') { $result='SIG_FAIL'; }
  244:     elsif ($result == '4') { $result='UNIT_FAIL'; }
  245:     elsif ($result == '5') { $result='NO_UNIT'; }
  246:     elsif ($result == '6') { $result='UNIT_OK'; }
  247:     elsif ($result == '7') { $result='INCORRECT'; }
  248:     elsif ($result == '8') { $result='UNIT_NOTNEEDED'; }
  249:     elsif ($result == '9') { $result='ANS_CNT_NOT_MATCH'; }
  250:     elsif ($result =='10') { $result='SUB_RECORDED'; }
  251:     elsif ($result =='11') { $result='BAD_FORMULA'; }
  252:     elsif ($result =='12' && !$response) { $result='MISSING_ANSWER'; }
  253:     elsif ($result =='12') { $result='WANTED_NUMERIC'; }
  254:     elsif ($result =='13') { $result='UNIT_INVALID_INSTRUCTOR'; }
  255:     elsif ($result =='141') { $result='UNIT_INVALID_STUDENT'; }
  256:     elsif ($result =='142') { $result='UNIT_INVALID_STUDENT'; }
  257:     elsif ($result =='143') { $result='UNIT_INVALID_STUDENT'; }
  258:     elsif ($result =='15') { $result='UNIT_IRRECONCIBLE'; }
  259:     else  {$result = "ERROR: Unknown Result:$result:$@:";}
  260: 
  261:     &LONCAPA_INTERNAL_DEBUG("RetError $reterror: Answer $answer: Response $response:  type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|");
  262:     &LONCAPA_INTERNAL_DEBUG(" $answer $response $result ");
  263:     return ($result,$reterror);
  264: }
  265: 
  266: 
  267: sub caparesponse_check_list {
  268:     my $responses=$LONCAPA::CAPAresponse_args{'response'};
  269:     &LONCAPA_INTERNAL_DEBUG("args ".join(':',%LONCAPA::CAPAresponse_args));
  270:     my $type = $LONCAPA::CAPAresponse_args{'type'};
  271:     my $answerunit=$LONCAPA::CAPAresponse_args{'unit'};
  272:     &LONCAPA_INTERNAL_DEBUG("Got type :$type: answer unit :$answerunit:\n");
  273:     
  274:     my $num_input_lines =
  275: 	scalar(@{$LONCAPA::CAPAresponse_answer->{'answers'}});
  276:     
  277:     if ($type ne '' ) {
  278: 	if (scalar(@$responses) < $num_input_lines) {
  279: 	    return 'MISSING_ANSWER';
  280: 	}
  281: 	if (scalar(@$responses) > $num_input_lines) {
  282: 	    return 'EXTRA_ANSWER';
  283: 	}
  284: 
  285:     }
  286: 
  287:     foreach my $which (0..($num_input_lines-1)) {
  288: 	my $answer_size = 
  289: 	    scalar(@{$LONCAPA::CAPAresponse_answer->{'answers'}[$which]});
  290: 	if ($type ne '' 
  291: 	    && $answer_size > 1) {
  292: 	    $responses->[$which]=[split(/,/,$responses->[$which])];
  293: 	} else {
  294: 	    $responses->[$which]=[$responses->[$which]];
  295: 	}
  296:     }
  297:     foreach my $which (0..($num_input_lines-1)) {
  298: 	my $answer_size = 
  299: 	    scalar(@{$LONCAPA::CAPAresponse_answer->{'answers'}[$which]});
  300: 	my $response_size = 
  301: 	    scalar(@{$responses->[$which]});
  302: 	if ($answer_size > $response_size) {
  303: 	    return 'MISSING_ANSWER';
  304: 	}
  305: 	if ($answer_size < $response_size) {
  306: 	    return 'EXTRA_ANSWER';
  307: 	}
  308:     }
  309: 
  310:     &LONCAPA_INTERNAL_DEBUG("Initial final response :$responses->[0][-1]:");
  311:     my $unit;
  312:     if ($type eq 'float' || $type eq '') {
  313: 	#for numerical problems split off the unit
  314: #	if ( $responses->[0][-1]=~ /(.*[^\s])\s+([^\s]+)/ ) {
  315:         if ( $responses->[0][-1]=~ /^([\d\.\,\s\$]*(?:(?:[xX\*]10[\^\*]*|[eE]*)[\+\-]*\d*)*(?:^|\S)\d+)([\$\s\w\^\*\/\(\)\+\-]*[^\d\.\s\,][\$\s\w\^\*\/\(\)\+\-]*)$/ ) {
  316: 	    $responses->[0][-1]=$1;
  317: 	    $unit=&capa_formula_fix($2);
  318:             &LONCAPA_INTERNAL_DEBUG("Found unit :$unit:");
  319: 	}
  320:     }
  321:     &LONCAPA_INTERNAL_DEBUG("Final final response :$responses->[0][-1]:$unit:");
  322:     $unit=~s/\s//;
  323:     foreach my $response (@$responses) {
  324:        foreach my $element (@$response) {	
  325:           if (($type eq 'float') || (($type eq '') && ($unit ne ''))) {
  326:               $element =~ s/\s//g;
  327:           }
  328:           my $appendunit=$unit;
  329:           if (($unit=~/\%/) && ($answerunit ne '%'))  {
  330:              $element=$element/100;
  331:              $appendunit=~s/\%//;
  332:           }    
  333:           if (($element==0) && ($unit!~/\w/) && ($answerunit=~/\w/)) {
  334:              $appendunit=$answerunit;
  335:           }
  336:           $element .= " $appendunit";
  337:           &LONCAPA_INTERNAL_DEBUG("Made response element :$element:");
  338:        }
  339:     }
  340:     
  341:     foreach my $thisanswer (@{ $LONCAPA::CAPAresponse_answer->{'answers'} }) {
  342: 	if (!defined($thisanswer)) {
  343: 	    return ('ERROR','answer was undefined');
  344: 	}
  345:     }
  346: 
  347: 
  348: #    &LONCAPA_INTERNAL_DEBUG(&LONCAPA_INTERNAL_Dumper($responses));
  349:     my %memoized;
  350:     if ($LONCAPA::CAPAresponse_answer->{'type'}  eq 'ordered') {
  351: 	for (my $i=0; $i<scalar(@$responses);$i++) {
  352: 	    my $answer   = $LONCAPA::CAPAresponse_answer->{'answers'}[$i];
  353: 	    my $response = $responses->[$i];
  354: 	    my $key = "$answer\0$response";
  355: 	    my (@awards,@msgs);
  356: 	    for (my $j=0; $j<scalar(@$response); $j++) { 
  357: 		my ($award,$msg) = &caparesponse_check($answer->[$j],
  358: 						       $response->[$j]);
  359: 		push(@awards,$award);
  360: 		push(@msgs,  $msg);
  361: 	    }
  362: 	    my ($award,$msg) = 
  363: 		&LONCAPA_INTERNAL_FINALIZEAWARDS(\@awards,\@msgs);
  364: 	    $memoized{$key} = [$award,$msg];
  365: 	}
  366:     } else {
  367: 	#FIXME broken with unorder responses where one is a <value>
  368:         #      and the other is a <vector> (need to delay parse til
  369:         #      inside the loop?)
  370: 	foreach my $response (@$responses) {
  371: 	    my $response_size = scalar(@{$response});
  372: 	    foreach my $answer (@{ $LONCAPA::CAPAresponse_answer->{'answers'} }) {
  373: 		my $key = "$answer\0$response";
  374: 		my $answer_size =  scalar(@{$answer});
  375: 		my ($award,$msg);
  376: 		if ($answer_size > $response_size) {
  377: 		    $award = 'MISSING_ANSWER';
  378: 		} elsif ($answer_size < $response_size) {
  379: 		    $award = 'EXTRA_ANSWER';
  380: 		} else {
  381: 		    my (@awards,@msgs);
  382: 		    for (my $j=0; $j<scalar(@$response); $j++) {
  383: 			my ($award,$msg) = &caparesponse_check($answer->[$j],
  384: 							       $response->[$j]);
  385: 			push(@awards,$award);
  386: 			push(@msgs,  $msg);
  387: 		    }
  388: 		    ($award,$msg) = 
  389: 			&LONCAPA_INTERNAL_FINALIZEAWARDS(\@awards,\@msgs);
  390: 		}
  391: 		$memoized{$key} = [$award,$msg];
  392: 	    }
  393: 	}
  394:     }
  395: 
  396:     my ($final_award,$final_msg);
  397:     &init_permutation(scalar(@$responses),
  398: 		      $LONCAPA::CAPAresponse_answer->{'type'});
  399: 
  400:     # possible FIXMEs
  401:     # - significant time is spent calling non-safe space routine
  402:     #   from safe space
  403:     # - early outs could be possible with classifying awards is to stratas
  404:     #   and stopping as so as hitting the top strata 
  405:     # - some early outs also might be possible with check ing the 
  406:     #   memoized hash of results (is correct even possible? etc.)
  407: 
  408:     my (@final_awards,@final_msg);
  409:     while( &get_permutations_left() ) {
  410: 	my $order = &get_next_permutation();
  411: 	my (@awards, @msgs, $i);
  412: 	foreach my $thisanswer (@{ $LONCAPA::CAPAresponse_answer->{'answers'} }) {
  413: 	    my $key = "$thisanswer\0".$responses->[$order->[$i]];
  414: 	    push(@awards,$memoized{$key}[0]);
  415: 	    push(@msgs,$memoized{$key}[1]);
  416: 	    $i++;
  417: 
  418: 	}
  419: 	&LONCAPA_INTERNAL_DEBUG(" all awards ".join(':',@awards));
  420: 
  421: 	my ($possible_award,$possible_msg) = 
  422: 	    &LONCAPA_INTERNAL_FINALIZEAWARDS(\@awards,\@msgs);
  423: 	&LONCAPA_INTERNAL_DEBUG(" pos awards ".$possible_award);
  424: 	push(@final_awards,$possible_award);
  425: 	push(@final_msg,$possible_msg);
  426:     }
  427: 
  428:     &LONCAPA_INTERNAL_DEBUG(" all final_awards ".join(':',@final_awards));
  429:     my ($final_award,$final_msg) = 
  430: 	&LONCAPA_INTERNAL_FINALIZEAWARDS(\@final_awards,\@final_msg,undef,1);
  431:     return ($final_award,$final_msg);
  432: }
  433: 
  434: sub cas {
  435:     my ($system,$input,$library)=@_;
  436:     my $output;
  437:     if ($system eq 'maxima') {
  438:        $output=&maxima_eval($input,$library);
  439:     } else {
  440:        $output='Error: unrecognized CAS';
  441:     }
  442:     return $output;
  443: }
  444: 
  445: sub tex {
  446:     if ( $external::target eq "tex" ) {
  447: 	return $_[0];
  448:     } else {
  449: 	return $_[1];
  450:     }
  451: }
  452: 
  453: sub var_in_tex {
  454:     if ( $external::target eq "tex" ) {
  455: 	return $_[0];
  456:     } else {
  457: 	return "";
  458:     }
  459: }
  460: 
  461: sub web {
  462:     if ( $external::target eq "tex" ) {
  463: 	return $_[1];
  464:     } else {
  465: 	if ( $external::target eq "web" || $external::target eq "answer") {
  466: 	    return $_[2];
  467: 	} else {
  468: 	    return $_[0];
  469: 	}
  470:     }
  471: }
  472: 
  473: sub html {
  474:     if ( $external::target eq "web" ) {
  475: 	return shift;
  476:     }
  477: }
  478: 
  479: sub hinton {
  480:     return 0;
  481: }
  482: 
  483: sub random {
  484:     my ($start,$end,$step)=@_;
  485:     if ( ! $hidden::RANDOMINIT ) {
  486: 	if ($external::randomseed == 0) { $external::randomseed=1; }
  487: 	if ($external::randomseed =~/,/) {
  488: 	    my ($num1,$num2)=split(/,/,$external::randomseed);
  489: 	    &random_set_seed(1,abs($num1));
  490: 	} elsif ($external::randomseed =~/:/) {
  491: 	    my ($num1,$num2)=split(/:/,$external::randomseed);
  492: 	    &random_set_seed(abs($num1),abs($num2));
  493: 	} else {
  494: 	    &random_set_seed(1,int(abs($external::randomseed)));
  495: 	}
  496: 	&math_random_uniform();
  497: 	$hidden::RANDOMINIT=1;
  498:     }
  499:     if (!defined($step)) { $step=1; }
  500:     my $num=1+int(($end-$start)/$step);
  501:     my $result=$start + int(&math_random_uniform() * $num)*$step;
  502:     return $result;
  503: }
  504: 
  505: sub random_normal {
  506:     my ($item_cnt,$seed,$av,$std_dev) = @_;
  507:     my @oldseed=&random_get_seed();
  508:     my @retArray;
  509:     &random_set_seed_from_phrase($seed);
  510:     @retArray=&math_random_normal($item_cnt,$av,$std_dev);
  511:     &random_set_seed(@oldseed);
  512:     return @retArray;
  513: }
  514: 
  515: sub random_beta {
  516:     my ($item_cnt,$seed,$aa,$bb) = @_;
  517:     my @oldseed=&random_get_seed();
  518:     my @retArray;
  519:     &random_set_seed_from_phrase($seed);
  520:     @retArray=&math_random_beta($item_cnt,$aa,$bb);
  521:     &random_set_seed(@oldseed);
  522:     return @retArray;
  523: }
  524: 
  525: sub random_gamma {
  526:     my ($item_cnt,$seed,$a,$r) = @_;
  527:     my @oldseed=&random_get_seed();
  528:     my @retArray;
  529:     &random_set_seed_from_phrase($seed);
  530:     @retArray=&math_random_gamma($item_cnt,$a,$r);
  531:     &random_set_seed(@oldseed);
  532:     return @retArray;
  533: }
  534: 
  535: sub random_exponential {
  536:     my ($item_cnt,$seed,$av) = @_;
  537:     my @oldseed=&random_get_seed();
  538:     my @retArray;
  539:     &random_set_seed_from_phrase($seed);
  540:     @retArray=&math_random_exponential($item_cnt,$av);
  541:     &random_set_seed(@oldseed);
  542:     return @retArray;
  543: }
  544: 
  545: sub random_poisson {
  546:     my ($item_cnt,$seed,$mu) = @_;
  547:     my @oldseed=&random_get_seed();
  548:     my @retArray;
  549:     &random_set_seed_from_phrase($seed);
  550:     @retArray=&math_random_poisson($item_cnt,$mu);
  551:     &random_set_seed(@oldseed);
  552:     return @retArray;
  553: }
  554: 
  555: sub random_chi {
  556:     my ($item_cnt,$seed,$df) = @_;
  557:     my @oldseed=&random_get_seed();
  558:     my @retArray;
  559:     &random_set_seed_from_phrase($seed);
  560:     @retArray=&math_random_chi_square($item_cnt,$df);
  561:     &random_set_seed(@oldseed);
  562:     return @retArray;
  563: }
  564: 
  565: sub random_noncentral_chi {
  566:     my ($item_cnt,$seed,$df,$nonc) = @_;
  567:     my @oldseed=&random_get_seed();
  568:     my @retArray;
  569:     &random_set_seed_from_phrase($seed);
  570:     @retArray=&math_random_noncentral_chi_square($item_cnt,$df,$nonc);
  571:     &random_set_seed(@oldseed);
  572:     return @retArray;
  573: }
  574: 
  575: sub random_f {
  576:     my ($item_cnt,$seed,$dfn,$dfd) = @_;
  577:     my @oldseed=&random_get_seed();
  578:     my @retArray;
  579:     &random_set_seed_from_phrase($seed);
  580:     @retArray=&math_random_f($item_cnt,$dfn,$dfd);
  581:     &random_set_seed(@oldseed);
  582:     return @retArray;
  583: }
  584: 
  585: sub random_noncentral_f {
  586:     my ($item_cnt,$seed,$dfn,$dfd,$nonc) = @_;
  587:     my @oldseed=&random_get_seed();
  588:     my @retArray;
  589:     &random_set_seed_from_phrase($seed);
  590:     @retArray=&math_random_noncentral_f($item_cnt,$dfn,$dfd,$nonc);
  591:     &random_set_seed(@oldseed);
  592:     return @retArray;
  593: }
  594: 
  595: sub random_multivariate_normal {
  596:     my ($item_cnt,$seed,$mean,$covar) = @_;
  597:     my @oldseed=&random_get_seed();
  598:     &random_set_seed_from_phrase($seed);
  599:     my @retArray=&math_random_multivariate_normal($item_cnt,@$mean,@$covar);
  600:     &random_set_seed(@oldseed);
  601:     return @retArray;
  602: }
  603: 
  604: sub random_multinomial {
  605:     my ($item_cnt,$seed,@p) = @_;
  606:     my @oldseed=&random_get_seed();
  607:     my @retArray;
  608:     &random_set_seed_from_phrase($seed);
  609:     my @retArray=&math_random_multinomial($item_cnt,@p);
  610:     &random_set_seed(@oldseed);
  611:     return @retArray;
  612: }
  613: 
  614: sub random_permutation {
  615:     my ($seed,@inArray) = @_;
  616:     my @oldseed=&random_get_seed();
  617:     my @retArray;
  618:     &random_set_seed_from_phrase($seed);
  619:     @retArray=&math_random_permutation(@inArray);
  620:     &random_set_seed(@oldseed);
  621:     return @retArray;
  622: }
  623: 
  624: sub random_uniform {
  625:     my ($item_cnt,$seed,$low,$high) = @_;
  626:     my @oldseed=&random_get_seed();
  627:     my @retArray;
  628:     &random_set_seed_from_phrase($seed);
  629:     @retArray=&math_random_uniform($item_cnt,$low,$high);
  630:     &random_set_seed(@oldseed);
  631:     return @retArray;
  632: }
  633: 
  634: sub random_uniform_integer {
  635:     my ($item_cnt,$seed,$low,$high) = @_;
  636:     my @oldseed=&random_get_seed();
  637:     my @retArray;
  638:     &random_set_seed_from_phrase($seed);
  639:     @retArray=&math_random_uniform_integer($item_cnt,$low,$high);
  640:     &random_set_seed(@oldseed);
  641:     return @retArray;
  642: }
  643: 
  644: sub random_binomial {
  645:     my ($item_cnt,$seed,$nt,$p) = @_;
  646:     my @oldseed=&random_get_seed();
  647:     my @retArray;
  648:     &random_set_seed_from_phrase($seed);
  649:     @retArray=&math_random_binomial($item_cnt,$nt,$p);
  650:     &random_set_seed(@oldseed);
  651:     return @retArray;
  652: }
  653: 
  654: sub random_negative_binomial {
  655:     my ($item_cnt,$seed,$ne,$p) = @_;
  656:     my @oldseed=&random_get_seed();
  657:     my @retArray;
  658:     &random_set_seed_from_phrase($seed);
  659:     @retArray=&math_random_negative_binomial($item_cnt,$ne,$p);
  660:     &random_set_seed(@oldseed);
  661:     return @retArray;
  662: }
  663: 
  664: sub abs { CORE::abs(shift) }
  665: sub sin { CORE::sin(shift) }
  666: sub cos { CORE::cos(shift) }
  667: sub exp { CORE::exp(shift) }
  668: sub int { CORE::int(shift) }
  669: sub log { CORE::log(shift) }
  670: sub atan2 { CORE::atan2($_[0],$_[1]) }
  671: sub sqrt { CORE::sqrt(shift) }
  672: 
  673: sub tan  { CORE::sin($_[0]) / CORE::cos($_[0]) }
  674: #sub atan { atan2($_[0], 1); }
  675: #sub acos { atan2(sqrt(1 - $_[0] * $_[0]), $_[0] ); }
  676: #sub asin { atan2($_[0], sqrt(1- $_[0] * $_[0]) );  }
  677: 
  678: sub log10 { CORE::log($_[0])/CORE::log(10); }
  679: 
  680: sub factorial {
  681:     my $input = CORE::int(shift);
  682:     return "Error - unable to take factorial of an negative number ($input)" if $input < 0;
  683:     return "Error - factorial result is greater than system limit ($input)" if $input > 170;
  684:     return 1 if $input == 0;
  685:     my $result = 1; 
  686:     for (my $i=2; $i<=$input; $i++) { $result *= $i }
  687:     return $result;
  688: }
  689: 
  690: sub sgn {
  691:     return -1 if $_[0] < 0;
  692:     return 0 if $_[0] == 0;
  693:     return 1 if $_[0] > 0;
  694: }
  695: 
  696: sub min {
  697:     my @sorted = sort { $a <=> $b || $a cmp $b } @_;
  698:     return shift @sorted;
  699: }
  700: 
  701: sub max {
  702:     my @sorted = sort { $a <=> $b || $a cmp $b } @_;
  703:     return pop @sorted;
  704: }
  705: 
  706: sub roundto {
  707:     my ($input,$n) = @_;
  708:     return sprintf('%.'.$n.'f',$input);
  709: }
  710: 
  711: sub to_string {
  712:     my ($input,$n) = @_;
  713:     return sprintf($input) if $n eq "";
  714:     $n = '.'.$n if $n !~ /^\./;
  715:     return sprintf('%'.$n,$input) if $n ne "";
  716: }
  717: 
  718: sub sub_string {
  719:     my ($str,$start,$len) = @_;
  720:     return substr($str,$start-1,$len);
  721: }
  722: 
  723: sub pow   {return $_[0] ** $_[1]; }
  724: sub ceil  {return (($_[0]-CORE::int($_[0]))== 0.0) ? $_[0] : (($_[0] > 0) ? (CORE::int($_[0])+ 1) : CORE::int($_[0])); }
  725: sub floor  {return (($_[0]-CORE::int($_[0]))== 0.0) ? $_[0] : (($_[0] > 0) ? CORE::int($_[0]) : (CORE::int($_[0])-1)); }
  726: #sub floor {return int($_[0]); }
  727: 
  728: sub format {
  729:     my ($value,$fmt)=@_;
  730:     my ($dollarmode,$commamode,$alwaysperiod,$options);
  731:     if ($fmt =~ /^([^\d]*)(.*)/) { $options=$1; $fmt=$2; } 
  732:     #if ($options =~ /\$/) { $dollamode=1; }
  733:     #if ($options =~ /,/)  { $commamode=1; }
  734:     if ($options =~ /\./) { $alwaysperiod=1; }
  735:     my $result;
  736:     if ($fmt=~/s$/i) {
  737: 	$result=&format_significant_figures($value,$fmt);
  738:     } else {
  739: 	$fmt=~s/e/E/g;
  740: 	$result=sprintf('%.'.$fmt,$value);
  741: 	if ($alwaysperiod && $fmt eq '0f') { $result .='.'; }
  742: 	$result=~s/(E[+-]*)0/$1/;
  743:     }
  744:     #if ($dollarmode) {$result=&dollarformat($result);}
  745:     #if ($commamode) {$result=&commaformat($result);}
  746:     return $result;
  747: }
  748: 
  749: sub chemparse {
  750:     my ($reaction) = @_;
  751:     my @tokens = split(/(\s\+|\->|<=>|<\-|\.)/,$reaction);
  752:     my $formula = '';
  753:     foreach my $token (@tokens) {
  754: 	if ($token eq '->' ) {
  755: 	    $formula .= '<m>\ensuremath{\rightarrow}</m> ';
  756: 	    next;
  757: 	}
  758: 	if ($token eq '<-' ) {
  759: 	    $formula .= '<m>\ensuremath{\leftarrow}</m> ';
  760: 	    next;
  761: 	}  
  762: 	if ($token eq '<=>') {
  763: 	    if ($external::target eq 'web' &&
  764: 		&EXT('request.browser.unicode')) {
  765: 		$formula .= '&#8652; ';
  766: 	    } else {
  767: 		$formula .= &web('<=> ','<m>\ensuremath{\rightleftharpoons}</m> ',
  768: 				 '&lt;=&gt; ');
  769: 	    }
  770: 	    next;
  771: 	}
  772: 	if ($token eq '.') {
  773: 	  $formula =~ s/(\&nbsp\;| )$//;
  774: 	  $formula .= '&middot;';
  775: 	  next;
  776: 	}
  777: 	$token =~ /^\s*([\d|\/]*(?:&frac\d\d)?)(.*)/;
  778:         $formula .= $1 if ($1 ne '1');  # stoichiometric coefficient
  779: 	
  780: 	my $molecule = $2;
  781: 	# subscripts
  782: 	$molecule =~ s|(?<=[a-zA-Z\)\]\s])(\d+)|<sub>$1</sub>|g;
  783: 	# superscripts
  784: 	$molecule =~ s|\^(\d*[+\-]*)|<sup>$1</sup>|g;
  785: 	# strip whitespace
  786: 	$molecule =~ s/\s*//g;
  787: 	# forced space
  788: 	$molecule =~ s/_/ /g;
  789: 	$molecule =~ s/-/&minus;/g;
  790: 	$formula .= $molecule.'&nbsp;';
  791:     }
  792:     # get rid of trailing space
  793:     $formula =~ s/(\&nbsp\;| )$//;
  794:     return &xmlparse($formula);
  795: }
  796: 
  797: sub prettyprint {
  798:     my ($value,$fmt,$target)=@_;
  799:     my $result;
  800:     if (!$target) { $target = $external::target; }
  801:     if ($fmt =~ /chem/i) { return(&chemparse($value)); }
  802:     my ($dollarmode,$commamode,$alwaysperiod,$options);
  803:     if ($fmt =~ /^([^\d]*)(.*)/) { $options=$1; $fmt=$2; } 
  804:     if ($options =~ /\$/) { $dollarmode=1; }
  805:     if ($options =~ /,/)  { $commamode=1; }
  806:     if ($options =~ /\./) { $alwaysperiod=1; }
  807:     if ($fmt=~/s$/i) {
  808: 	$value=&format_significant_figures($value,$fmt);
  809:     } elsif ($fmt) {
  810: 	$value=sprintf('%.'.$fmt,$value);
  811:     }
  812:     if ($alwaysperiod && $fmt eq '0f') {
  813: 	if ($target eq 'tex') {
  814: 	    $value .='\\ensuremath{.}';
  815: 	} else {
  816: 	    $value .='.';
  817: 	}
  818:     }
  819:     if ($value =~ /([0-9\.\-\+]+)E([0-9\-\+]+)/i ) {
  820: 	my $frac=$1;
  821: 	if ($dollarmode) { $frac=&dollarformat($frac); }
  822: 	if ($commamode) { $frac=&commaformat($frac); }
  823: 	my $exponent=$2;
  824: 	$exponent=~s/^\+0*//;
  825: 	$exponent=~s/^-0*/-/;
  826: 	$exponent=~s/^-0*/-/;
  827: 	if ($exponent eq '-') { undef($exponent); }
  828: 	if ($exponent) {
  829: 	    if ($target eq 'web') {
  830: 		$result=$frac.'&#215;10<sup>'.$exponent.'</sup>';
  831: 	    } elsif ($target eq 'tex') {
  832: 		$result='\ensuremath{'.$frac.'\times 10^{'.$exponent.'}}';
  833: 	    } else {
  834: 		$result=$value;
  835: 	    }
  836: 	} else {
  837: 	    $result=$frac;
  838: 	}
  839:     } else {
  840: 	$result=$value;
  841: 	if    ($dollarmode) { $result=&dollarformat($result,$target); }
  842: 	elsif ($commamode)  { $result=&commaformat($result,$target); }
  843:     }
  844:     return $result;
  845: }
  846: 
  847: sub commaformat {
  848:     my ($number,$target) = @_;
  849:     if ($number =~ /\./) {
  850: 	while ($number =~ /([^0-9]*)([0-9]+)([^\.,][^\.,][^\.,])([,0-9]*\.[0-9]*)$/) {
  851: 	    $number = $1.$2.','.$3.$4;
  852: 	}
  853:     } else {
  854: 	while ($number =~ /^([^0-9]*)([0-9]+)([^,][^,][^,])([,0-9]*)$/) {
  855: 	    $number = $1.$2.','.$3.$4;
  856: 	}
  857:     }
  858:     return $number;
  859: }
  860: 
  861: sub dollarformat {
  862:     my ($number,$target) = @_;
  863:     if (!$target) { $target = $external::target; }
  864:     $number=&commaformat($number,$target);
  865:     if ($target eq 'tex') {
  866: 	$number='\$'.$number; #' stupid emacs
  867:     } else {
  868: 	$number='$'.$number; #' stupid emacs
  869:     }
  870:     return $number; 
  871: }
  872: 
  873: # format of form ns or nS where n is an integer
  874: sub format_significant_figures {
  875:     my ($number,$format) = @_; 
  876:     return '0' if ($number == 0);
  877:     # extract number of significant figures needed
  878:     my ($sig) = ($format =~ /(\d+)s/i);
  879:     # arbitrary choice - suggestions ?? or throw error message?
  880:     $sig = 3 if ($sig eq '');
  881:     # save the minus sign
  882:     my $sign = ($number < 0) ? '-' : '';
  883:     $number = abs($number);
  884:     # needed to correct for a number greater than 1 (or
  885:     my $power = ($number < 1) ? 0 : 1;
  886:     # could round up. Take the integer part of log10.
  887:     my $x10 = int(log($number)/log(10));
  888:     # find number with values left of decimal pt = # of sign figs.
  889:     my $xsig = $number*10**($sig-$x10-$power);
  890:     # get just digits left of decimal pt - also rounds off correctly
  891:     my $xint  = sprintf('%.0f',$xsig);
  892:     # save any trailing zero's
  893:     my ($zeros) = ($xint =~ /(0+)$/);
  894:     # return number to original magnitude
  895:     my $numSig = $xint*10**($x10-$sig+$power);
  896:     # insert trailing zero's if have decimal point
  897:     $numSig =~ s/^(\d+)\.(\d+)(\e?(.*)?)$/$1\.$2$zeros$3/;
  898:     # put a decimal pt for number ending with 0 and length = # of sig fig
  899:     $numSig.='.' if (length($numSig) == $sig && $numSig =~ /0$/);
  900:     if (length($numSig) < $sig) {
  901: 	$numSig.='.'.substr($zeros,0,($sig-length($numSig)));
  902:     }
  903:     # return number with sign
  904:     return $sign.$numSig;
  905: 
  906: }
  907: 
  908: sub map {
  909:     my ($phrase,$dest,$source)=@_;
  910:     my @oldseed=&random_get_seed();
  911:     my @seed = &random_seed_from_phrase($phrase);
  912:     &random_set_seed(@seed);
  913:     my $destct = scalar(@$dest);
  914:     if (!$source) {
  915: 	my @output;
  916: 	my @idx = &math_random_permuted_index($destct);
  917: 	my $ctr = 0;
  918: 	while ($ctr < $destct) {
  919: 	    $output[$ctr] = $$dest[$idx[$ctr]];
  920: 	    $ctr++;
  921: 	}
  922:         &random_set_seed(@oldseed);
  923: 	return @output;
  924:     } else {
  925: 	my $num = scalar(@$source);
  926: 	my @idx = &math_random_permuted_index($num);
  927: 	my $ctr = 0;
  928: 	my $tot = $num;
  929: 	$tot = $destct if $destct < $num;
  930: 	if (ref($$dest[0])) {
  931: 	    while ($ctr < $tot) {
  932: 		${$$dest[$ctr]} = $$source[$idx[$ctr]];
  933: 	        $ctr++;
  934:             }
  935:         } else {
  936: 	    while ($ctr < $tot) {
  937: 		$$dest[$ctr] = $$source[$idx[$ctr]];
  938: 		$ctr++;
  939: 	    }
  940: 	}
  941:     }
  942:     &random_set_seed(@oldseed);
  943:     return '';
  944: }
  945: 
  946: sub rmap {
  947:     my ($phrase,$dest,$source)=@_;
  948:     my @oldseed=&random_get_seed();
  949:     my @seed = &random_seed_from_phrase($phrase);
  950:     &random_set_seed(@seed);
  951:     my $destct = scalar(@$dest);
  952:     if (!$source) {
  953: 	my @idx = &math_random_permuted_index($destct);
  954: 	my $ctr = 0;
  955: 	my @r_idx;
  956: 	while ($ctr < $destct) {
  957: 	    $r_idx[$idx[$ctr]] = $ctr;
  958: 	    $ctr++;
  959: 	}
  960: 	my @output;
  961: 	$ctr = 0;
  962: 	while ($ctr < $destct) {
  963: 	    $output[$ctr] = $$dest[$r_idx[$ctr]];
  964: 	    $ctr++;
  965: 	}
  966:         &random_set_seed(@oldseed);
  967: 	return @output;
  968:     } else {
  969: 	my $num = scalar(@$source);
  970: 	my @idx = &math_random_permuted_index($num);
  971: 	my $ctr = 0;
  972: 	my $tot = $num;
  973: 	$tot = $destct if $destct < $num;
  974: 	my @r_idx;
  975: 	while ($ctr < $tot) {
  976: 	    $r_idx[$idx[$ctr]] = $ctr;
  977: 	    $ctr++;
  978: 	}
  979: 	$ctr = 0;
  980: 	if (ref($$dest[0])) {
  981: 	    while ($ctr < $tot) {
  982: 		${$$dest[$ctr]} = $$source[$r_idx[$ctr]];
  983: 	        $ctr++;
  984:             }
  985:         } else {
  986: 	    while ($ctr < $tot) {
  987: 		$$dest[$ctr] = $$source[$r_idx[$ctr]];
  988: 		$ctr++;
  989: 	    }
  990: 	}
  991:     }
  992:     &random_set_seed(@oldseed);
  993:     return '';
  994: }
  995: 
  996: sub capa_id { return }
  997: 
  998: sub problem { return }
  999: 
 1000: sub name{
 1001:     my $fullname = &EXT('environment.lastname').', '.&EXT('environment.firstname').' '.&EXT('environment.middlename');
 1002:     $fullname = "" if $fullname eq ",  ";
 1003:     $fullname =~ s/\%2d/-/g;
 1004:     return $fullname;
 1005: }
 1006: 
 1007: sub student_number { 
 1008:     my $id = &EXT('environment.id');
 1009:     $id = '' if $id eq "";
 1010:     return $id;
 1011: }
 1012: 
 1013: sub class {
 1014:     my $course = &EXT('course.description');
 1015:     $course = '' if $course eq "";
 1016:     return $course;
 1017: }
 1018: 
 1019: sub firstname {
 1020:     my $firstname = &EXT('environment.firstname');
 1021:     $firstname = '' if $firstname eq "";
 1022:     return $firstname;
 1023: }
 1024:                                                                                 
 1025: sub lastname {
 1026:     my $lastname = &EXT('environment.lastname');
 1027:     $lastname = '' if $lastname eq "";
 1028:     return $lastname;
 1029: }
 1030: 
 1031: sub sec { 
 1032:     my $sec = &EXT('request.course.sec');
 1033:     $sec = '' if $sec eq "";
 1034:     return $sec;
 1035: }
 1036: 
 1037: sub submission {
 1038:    my ($partid,$responseid,$subnumber)=@_;
 1039:    my $sub='';
 1040:    if ($subnumber) { $sub=$subnumber.':'; }
 1041:    return &EXT('user.resource.'.$sub.'resource.'.$partid.'.'.$responseid.'.submission');
 1042: }
 1043: 
 1044: sub currentpart {
 1045:    return $external::part;
 1046: }
 1047: 
 1048: sub eval_time {
 1049:    my ($timestamp)=@_;
 1050:    unless ($timestamp) { return ''; }
 1051:    return &locallocaltime($timestamp);
 1052: }
 1053: 
 1054: sub open_date { 
 1055:     my ($partid)=@_;
 1056:     unless ($partid) { $partid=0; }
 1057:     return &eval_time(&EXT('resource.'.$partid.'.opendate'));
 1058: }
 1059: 
 1060: sub due_date {
 1061:     my ($partid)=@_;
 1062:     unless ($partid) { $partid=0; } 
 1063:     return &eval_time(&EXT('resource.'.$partid.'.duedate'));
 1064: }
 1065: 
 1066: sub answer_date { 
 1067:     my ($partid)=@_;
 1068:     unless ($partid) { $partid=0; }
 1069:     return &eval_time(&EXT('resource.'.$partid.'.answerdate'));
 1070: }
 1071: 
 1072: sub open_date_epoch {
 1073:     my ($partid)=@_;
 1074:     unless ($partid) { $partid=0; }
 1075:     return &EXT('resource.'.$partid.'.opendate');
 1076: }
 1077: 
 1078: sub due_date_epoch {
 1079:     my ($partid)=@_;
 1080:     unless ($partid) { $partid=0; }
 1081:     return &EXT('resource.'.$partid.'.duedate');
 1082: }
 1083: 
 1084: sub answer_date_epoch {
 1085:     my ($partid)=@_;
 1086:     unless ($partid) { $partid=0; }
 1087:     return &EXT('resource.'.$partid.'.answerdate');
 1088: }
 1089: 
 1090: sub array_moments {
 1091:     my @input=@_;
 1092:     my (@output,$N);
 1093:     $N=scalar (@input);
 1094:     $output[0]=$N;
 1095:     if ($N <= 1) {
 1096: 	$output[1]=$input[0];
 1097: 	$output[1]="Input array not defined" if ($N == 0);
 1098: 	$output[2]="variance undefined for N<=1";
 1099: 	$output[3]="skewness undefined for N<=1";
 1100: 	$output[4]="kurtosis undefined for N<=1";
 1101: 	return @output;
 1102:     }
 1103:     my $sum=0;
 1104:     foreach my $line (@input) {
 1105: 	$sum+=$line;
 1106:     }
 1107:     $output[1] = $sum/$N;
 1108:     my ($x,$sdev,$var,$skew,$kurt) = 0;
 1109:     foreach my $line (@input) {
 1110: 	$x=$line-$output[1];
 1111: 	$var+=$x**2;
 1112: 	$skew+=$x**3;
 1113: 	$kurt+=$x**4;
 1114:     }
 1115:     $output[2]=$var/($N-1);
 1116:     $sdev=CORE::sqrt($output[2]);
 1117:     if ($sdev == 0) {
 1118: 	$output[3]="inf-variance=0";
 1119: 	$output[4]="inf-variance=0";
 1120: 	return @output;
 1121:     }
 1122:     $output[3]=$skew/($sdev**3*$N);
 1123:     $output[4]=$kurt/($sdev**4*$N)-3;
 1124:     return @output;
 1125: }
 1126: 
 1127: sub choose {
 1128:     my $num = $_[0];
 1129:     return $_[$num];
 1130: }
 1131: 
 1132: #&sum1(1,$x,sub { &sum1($_[0],2*$_[0], sub { fact($_[0])**2 })});
 1133: #sub sum1 {
 1134: #    my ($start,$end,$sub)=@_;
 1135: #    my $sum=0;
 1136: #    for (my $i=$start;$i<=$end;$i++) {
 1137: #        $sum+=&$sub($i);
 1138: #    }
 1139: #    return $sum
 1140: #}
 1141: 
 1142: #&sum2('a',1,$x,'&sum2(\'b\',$a,2*$a, \'&factorial($b)**2\')');
 1143: #sub sum2 {
 1144: #    my ($varname,$start,$end,$line)=@_;
 1145: #    my $sum=0;
 1146: #    for (my $i=$start;$i<=$end;$i++) {
 1147: #	my $func=sub {
 1148: #	    eval("\$".$varname."=$i");
 1149: #	    eval($line);
 1150: #	};
 1151: #        $sum+=&$func($i);
 1152: #    }
 1153: #    return $sum
 1154: #}
 1155: 
 1156: # expiremental idea
 1157: sub proper_path {
 1158:     my ($path)=@_;
 1159:     if ( $external::target eq "tex" ) {
 1160: 	return '/home/httpd/html'.$path;
 1161:     } else {
 1162: 	return $path;
 1163:     }
 1164: }
 1165: 

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