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 1.54 2002/11/13 23:05:46 albertel 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: # Guy Albertelli
30: #
31: # 05/25/2001 H. K. Ng
32: # 05/31/2001 H. K. Ng
33: # 12/21/2001 Matthew
34: #
35: #init some globals
36: $hidden::RANDOMINIT=0;
37: $pi=atan2(1,1)*4;
38: $rad2deg=180.0/$pi;
39: $deg2rad=$pi/180.0;
40: $"=' ';
41:
42: sub caparesponse_check {
43: #not properly used yet: calc
44: #not to be used: $ans_fmt
45: my ($answer,$type,$tol,$sig,$ans_fmt,$unit,$calc,$samples) =
46: eval $_[1].
47: ';return ($answer,$type,$tol,$sig,$ans_fmt,$unit,$calc,$samples);';
48:
49: my $tol_type=''; # gets it's value from whether tol has a % or not done
50: my $sig_lbound=''; #done
51: my $sig_ubound=''; #done
52: my ($response,$expr)=@_;
53:
54:
55: #type's definitons come from capaParser.h
56: my $message='';
57: #remove leading and trailing whitespace
58: if ($response=~ /^\s|\s$/) {
59: $response=~ s:^\s+|\s+$::g;
60: $message .="Removed ws now :$response:\n";
61: } else {
62: $message .="no ws in :$response:\n";
63: }
64:
65: if ($type eq '' ) {
66: $message .= "Didn't find a type :$type:$expr: defaulting\n";
67: if ( $answer eq ($answer *1.0)) { $type = 2;
68: } else { $type = 3; }
69: } else {
70: if ($type eq 'cs') { $type = 4;
71: } elsif ($type eq 'ci') { $type = 3;
72: } elsif ($type eq 'mc') { $type = 5;
73: } elsif ($type eq 'fml') { $type = 8;
74: } elsif ($type eq 'subj') { $type = 7;
75: } elsif ($type eq 'float') { $type = 2;
76: } elsif ($type eq 'int') { $type = 1;
77: } else { return "ERROR: Unknown type of answer: $type" }
78: }
79:
80: my $points;
81: my $id_list;
82: #formula type setup the sample points
83: if ($type eq '8') {
84: ($id_list,$points)=split(/@/,$samples);
85: $message.="Found :$points: points\n";
86: }
87: if ($tol eq '') {
88: $tol=0.0;
89: $tol_type=1; #TOL_ABSOLUTE
90: } else {
91: if ($tol =~ /%$/) {
92: chop $tol;
93: $tol_type=2; #TOL_PERCENTAGE
94: } else {
95: $tol_type=1; #TOL_ABSOLUTE
96: }
97: }
98:
99: if ($sig eq '') {
100: $sig_lbound = 0; #SIG_LB_DEFAULT
101: $sig_ubound =15; #SIG_UB_DEFAULT
102: } else {
103: ($sig_lbound,$sig_ubound) = split /,/,$sig;
104: if (!defined($sig_lbound)) {
105: $sig_lbound = 0; #SIG_LB_DEFAULT
106: $sig_ubound =15; #SIG_UB_DEFAULT
107: }
108: if (!defined($sig_ubound)) { $sig_ubound=$sig_lbound; }
109: }
110: my $result = &caparesponse_capa_check_answer($response,$answer,$type,
111: $tol_type,$tol,
112: $sig_lbound,$sig_ubound,
113: $ans_fmt,$unit,$calc,$id_list,
114: $points,$external::randomseed);
115:
116: if ($result == '1') { $result='EXACT_ANS'; }
117: elsif ($result == '2') { $result='APPROX_ANS'; }
118: elsif ($result == '3') { $result='SIG_FAIL'; }
119: elsif ($result == '4') { $result='UNIT_FAIL'; }
120: elsif ($result == '5') { $result='NO_UNIT'; }
121: elsif ($result == '6') { $result='UNIT_OK'; }
122: elsif ($result == '7') { $result='INCORRECT'; }
123: elsif ($result == '8') { $result='UNIT_NOTNEEDED'; }
124: elsif ($result == '9') { $result='ANS_CNT_NOT_MATCH'; }
125: elsif ($result =='10') { $result='SUB_RECORDED'; }
126: elsif ($result =='11') { $result='BAD_FORMULA'; }
127: elsif ($result =='12') { $result='WANTED_NUMERIC'; }
128: else {$result = "ERROR: Unknown Result:$result:$@:";}
129:
130: return "$result:\nError $error:\nAnswer $answer:\nResponse $response:\n type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|\n$message$expr";
131: }
132:
133: sub get_array_args {
134: my ($expr,$arg)=@_;
135: # do these first, because who knows what varname the instructor might have used
136: # but it probably isn't $CAPARESPONSE_CHECK_LIST_answer
137: my $CAPARESPONSE_CHECK_LIST_answer = eval $expr.';return $'.$arg; #'
138: my $GET_ARRAY_ARGS_result;
139: my @GET_ARRAY_ARGS_list;
140: if ($CAPARESPONSE_CHECK_LIST_answer =~ /^\s*[\$\@]/) {
141: (@GET_ARRAY_ARGS_list) = eval $CAPARESPONSE_CHECK_LIST_answer;
142: }
143: $GET_ARRAY_ARGS_result.="error:$@:\n";
144: # if the eval fails just use what is in the answer exactly
145: if (!defined(@GET_ARRAY_ARGS_list) || !defined($GET_ARRAY_ARGS_list[0])) {
146: $GET_ARRAY_ARGS_result.="list zero is undefined\n";
147: $GET_ARRAY_ARGS_list[0]=$CAPARESPONSE_CHECK_LIST_answer;
148: }
149: return $GET_ARRAY_ARGS_result,@GET_ARRAY_ARGS_list;
150: }
151:
152: sub caparesponse_check_list {
153: my ($response,$expr)=@_;
154: my $result;
155: my ($result,@list) = &get_array_args($expr,'answer');
156: my $aresult='';
157: my $current_answer;
158: my $answers=join(':',@list);
159: $result.="Got response :$answers:\n";
160: my @responselist;
161: my $type =eval $expr.';return $answer;';
162: if ($type ne '' && $#list > 0) {
163: (@responselist)=split /,/,$response;
164: } else {
165: (@responselist)=($response);
166: }
167: my $unit='';
168: $result.="Initial final response :$responselist['-1']:\n";
169: if ($type eq '') {
170: #for numerical problems split off the unit
171: if ( $responselist['-1']=~ /(.*[^\s])\s+([^\s]+)/ ) {
172: $responselist['-1']=$1;
173: $unit=$2;
174: }
175: }
176: $result.="Final final response :$responselist['-1']:\n";
177: $result.=":$#list: answers\n";
178: $unit=~s/\s//;
179: my $i=0;
180: my $awards='';
181: for ($i=0; $i<@list;$i++) {
182: $result.="trying answer :$list[$i]:\n";
183: if ($unit eq '') {
184: $aresult=&caparesponse_check($responselist[$i],
185: $expr.';my $answer=\''.$list[$i].'\';');
186: } else {
187: $aresult=&caparesponse_check($responselist[$i]." $unit",
188: $expr.';my $answer=\''.$list[$i].'\';');
189: }
190: my ($temp)=split /:/, $aresult;
191: $awards.="$temp,";
192: $result.=$aresult;
193: }
194: chop $awards;
195: return "$awards:\n$result";
196: }
197:
198: sub tex {
199: if ( $external::target eq "tex" ) {
200: return @_[0];
201: } else {
202: return @_[1];
203: }
204: }
205:
206: sub var_in_tex {
207: if ( $external::target eq "tex" ) {
208: return @_[0];
209: } else {
210: return "";
211: }
212: }
213:
214: sub web {
215: if ( $external::target eq "tex" ) {
216: return @_[1];
217: } else {
218: if ( $external::target eq "web" || $external::target eq "answer") {
219: return @_[2];
220: } else {
221: return @_[0];
222: }
223: }
224: }
225:
226: sub html {
227: if ( $external::target eq "web" ) {
228: return shift;
229: }
230: }
231:
232: sub problem {
233: return '1';
234: }
235:
236: sub hinton {
237: return 0;
238: }
239:
240: sub random {
241: my ($start,$end,$step)=@_;
242: if ( ! $hidden::RANDOMINIT ) {
243: &random_set_seed(1,$external::randomseed);
244: &math_random_uniform();
245: $hidden::RANDOMINIT=1;
246: }
247: if (!defined($step)) { $step=1; }
248: my $num=1+int(($end-$start)/$step);
249: my $result=$start + int(&math_random_uniform() * $num)*$step;
250: return $result;
251: }
252:
253: sub random_normal {
254: my ($item_cnt,$seed,$av,$std_dev) = @_;
255: my @oldseed=&random_get_seed();
256: my @retArray;
257: &random_set_seed_from_phrase($seed);
258: @retArray=&math_random_normal($item_cnt,$av,$std_dev);
259: &random_set_seed(@oldseed);
260: return @retArray;
261: }
262:
263: sub random_beta {
264: my ($item_cnt,$seed,$aa,$bb) = @_;
265: my @oldseed=&random_get_seed();
266: my @retArray;
267: &random_set_seed_from_phrase($seed);
268: @retArray=&math_random_beta($item_cnt,$aa,$bb);
269: &random_set_seed(@oldseed);
270: return @retArray;
271: }
272:
273: sub random_gamma {
274: my ($item_cnt,$seed,$a,$r) = @_;
275: my @oldseed=&random_get_seed();
276: my @retArray;
277: &random_set_seed_from_phrase($seed);
278: @retArray=&math_random_gamma($item_cnt,$a,$r);
279: &random_set_seed(@oldseed);
280: return @retArray;
281: }
282:
283: sub random_exponential {
284: my ($item_cnt,$seed,$av) = @_;
285: my @oldseed=&random_get_seed();
286: my @retArray;
287: &random_set_seed_from_phrase($seed);
288: @retArray=&math_random_exponential($item_cnt,$av);
289: &random_set_seed(@oldseed);
290: return @retArray;
291: }
292:
293: sub random_poisson {
294: my ($item_cnt,$seed,$mu) = @_;
295: my @oldseed=&random_get_seed();
296: my @retArray;
297: &random_set_seed_from_phrase($seed);
298: @retArray=&math_random_poisson($item_cnt,$mu);
299: &random_set_seed(@oldseed);
300: return @retArray;
301: }
302:
303: sub random_chi {
304: my ($item_cnt,$seed,$df) = @_;
305: my @oldseed=&random_get_seed();
306: my @retArray;
307: &random_set_seed_from_phrase($seed);
308: @retArray=&math_random_chi_square($item_cnt,$df);
309: &random_set_seed(@oldseed);
310: return @retArray;
311: }
312:
313: sub random_noncentral_chi {
314: my ($item_cnt,$seed,$df,$nonc) = @_;
315: my @oldseed=&random_get_seed();
316: my @retArray;
317: &random_set_seed_from_phrase($seed);
318: @retArray=&math_random_noncentral_chi_square($item_cnt,$df,$nonc);
319: &random_set_seed(@oldseed);
320: return @retArray;
321: }
322:
323: sub random_f {
324: my ($item_cnt,$seed,$dfn,$dfd) = @_;
325: my @oldseed=&random_get_seed();
326: my @retArray;
327: &random_set_seed_from_phrase($seed);
328: @retArray=&math_random_f($item_cnt,$dfn,$dfd);
329: &random_set_seed(@oldseed);
330: return @retArray;
331: }
332:
333: sub random_noncentral_f {
334: my ($item_cnt,$seed,$dfn,$dfd,$nonc) = @_;
335: my @oldseed=&random_get_seed();
336: my @retArray;
337: &random_set_seed_from_phrase($seed);
338: @retArray=&math_random_noncentral_f($item_cnt,$dfn,$dfd,$nonc);
339: &random_set_seed(@oldseed);
340: return @retArray;
341: }
342:
343: sub random_multivariate_normal {
344: my ($item_cnt,$seed,$mean,$covar) = @_;
345: my @oldseed=&random_get_seed();
346: &random_set_seed_from_phrase($seed);
347: @retArray=&math_random_multivariate_normal($item_cnt,@$mean,@$covar);
348: &random_set_seed(@oldseed);
349: return @retArray;
350: }
351:
352: sub random_multinomial {
353: my ($item_cnt,$seed,@p) = @_;
354: my @oldseed=&random_get_seed();
355: my @retArray;
356: &random_set_seed_from_phrase($seed);
357: @retArray=&math_random_multinomial($item_cnt,@p);
358: &random_set_seed(@oldseed);
359: return @retArray;
360: }
361:
362: sub random_permutation {
363: my ($seed,@inArray) = @_;
364: my @oldseed=&random_get_seed();
365: my @retArray;
366: &random_set_seed_from_phrase($seed);
367: @retArray=&math_random_permutation(@inArray);
368: &random_set_seed(@oldseed);
369: return @retArray;
370: }
371:
372: sub random_uniform {
373: my ($item_cnt,$seed,$low,$high) = @_;
374: my @oldseed=&random_get_seed();
375: my @retArray;
376: &random_set_seed_from_phrase($seed);
377: @retArray=&math_random_uniform($item_cnt,$low,$high);
378: &random_set_seed(@oldseed);
379: return @retArray;
380: }
381:
382: sub random_uniform_integer {
383: my ($item_cnt,$seed,$low,$high) = @_;
384: my @oldseed=&random_get_seed();
385: my @retArray;
386: &random_set_seed_from_phrase($seed);
387: @retArray=&math_random_uniform_integer($item_cnt,$low,$high);
388: &random_set_seed(@oldseed);
389: return @retArray;
390: }
391:
392: sub random_binomial {
393: my ($item_cnt,$seed,$nt,$p) = @_;
394: my @oldseed=&random_get_seed();
395: my @retArray;
396: &random_set_seed_from_phrase($seed);
397: @retArray=&math_random_binomial($item_cnt,$nt,$p);
398: &random_set_seed(@oldseed);
399: return @retArray;
400: }
401:
402: sub random_negative_binomial {
403: my ($item_cnt,$seed,$ne,$p) = @_;
404: my @oldseed=&random_get_seed();
405: my @retArray;
406: &random_set_seed_from_phrase($seed);
407: @retArray=&math_random_negative_binomial($item_cnt,$ne,$p);
408: &random_set_seed(@oldseed);
409: return @retArray;
410: }
411:
412: sub abs { abs(shift) }
413: sub sin { sin(shift) }
414: sub cos { cos(shift) }
415: sub exp { exp(shift) }
416: sub int { int(shift) }
417: sub log { log(shift) }
418: sub atan2 { atan2($_[0],$_[1]) }
419: sub sqrt { sqrt(shift) }
420:
421: sub tan { sin($_[0]) / cos($_[0]) }
422: #sub atan { atan2($_[0], 1); }
423: #sub acos { atan2(sqrt(1 - $_[0] * $_[0]), $_[0] ); }
424: #sub asin { atan2($_[0], sqrt(1- $_[0] * $_[0]) ); }
425:
426: sub log10 { log($_[0])/log(10); }
427:
428: sub factorial {
429: my $input = int(shift);
430: return "Error - unable to take factorial of an negative number ($input)" if $input < 0;
431: return "Error - factorial result is greater than system limit ($input)" if $input > 170;
432: return 1 if $input == 0;
433: my $result = 1;
434: for (my $i=2; $i<=$input; $i++) { $result *= $i }
435: return $result;
436: }
437:
438: sub sgn {
439: return -1 if $_[0] < 0;
440: return 0 if $_[0] == 0;
441: return 1 if $_[0] > 0;
442: }
443:
444: sub min {
445: my @sorted = sort { $a <=> $b || $a cmp $b } @_;
446: return shift @sorted;
447: }
448:
449: sub max {
450: my @sorted = sort { $a <=> $b || $a cmp $b } @_;
451: return pop @sorted;
452: }
453:
454: sub roundto {
455: my ($input,$n) = @_;
456: return sprintf('%.'.$n.'f',$input);
457: }
458:
459: sub to_string {
460: my ($input,$n) = @_;
461: return sprintf($input) if $n eq "";
462: $n = '.'.$n if $n !~ /^\./;
463: return sprintf('%'.$n,$input) if $n ne "";
464: }
465:
466: sub sub_string {
467: my ($str,$start,$len) = @_;
468: return substr($str,$start-1,$len);
469: }
470:
471: sub pow {return $_[0] ** $_[1]; }
472: sub ceil {return (($_[0]-int($_[0]))== 0.0) ? $_[0] : (($_[0] > 0) ? (int($_[0])+ 1) : int($_[0])); }
473: sub floor {return (($_[0]-int($_[0]))== 0.0) ? $_[0] : (($_[0] > 0) ? int($_[0]) : (int($_[0])-1)); }
474: #sub floor {return int($_[0]); }
475:
476: sub format {
477: my ($value,$fmt)=@_;
478: my $dollarmode;
479: if ($fmt =~ /^\$(.*)/) { $fmt=$1; $dollarmode=1; }
480: my $result=sprintf('%.'.$fmt,$value);
481: $result=~s/(E[+-]*)0/$1/;
482: if ($dollarmode) {$result=&dollarmode($result);}
483: return $result;
484: }
485:
486: sub prettyprint {
487: my ($value,$fmt)=@_;
488: my $result;
489: my $dollarmode;
490: if ($fmt =~ /^\$(.*)/) { $fmt=$1; $dollarmode=1; }
491: if ($fmt) { $value=sprintf('%.'.$fmt,$value); }
492: if ($value =~ /([0-9\.\-\+]+)E([0-9\-\+]+)/ ) {
493: my $frac=$1;
494: if ($dollarmode) { $frac=&dollarformat($frac); }
495: my $exponent=$2;
496: $exponent=~s/^\+0*//;
497: $exponent=~s/^-0*/-/;
498: if ($exponent) {
499: if ($external::target eq 'web') {
500: $result=$frac.'×10<sup>'.$exponent.'</sup>';
501: } elsif ($external::target eq 'tex') {
502: $result='\ensuremath{'.$frac.'\times 10^{'.$exponent.'}}';
503: } else {
504: $result=$value;
505: }
506: } else {
507: $result=$frac;
508: }
509: } else {
510: $result=$value;
511: if ($dollarmode) { $result=&dollarformat($result); }
512: }
513: return $result;
514: }
515:
516: sub dollarformat {
517: my ($number) = @_;
518: if ($number =~ /\./) {
519: while ($number =~ /([^\.,]+)([^\.,][^\.,][^\.,])([,0-9]*\.[0-9]*$)/) {
520: $number = $1.','.$2.$3;
521: }
522: } else {
523: while ($number =~ /([^,]+)([^,][^,][^,])([,0-9]*)$/) {
524: $number = $1.','.$2.$3;
525: }
526: }
527: if ($external::target eq 'tex') {
528: $number='\$'.$number; #' stupid emacs
529: } else {
530: $number='$'.$number; #' stupid emacs
531: }
532: return $number;
533: }
534:
535: sub map {
536: my ($phrase,$dest,$source)=@_;
537: my @oldseed=&random_get_seed();
538: my @seed = &random_seed_from_phrase($phrase);
539: &random_set_seed(@seed);
540: my $destct = scalar(@$dest);
541: if (!$source) {
542: my @output;
543: my @idx = &math_random_permuted_index($destct);
544: my $ctr = 0;
545: while ($ctr < $destct) {
546: $output[$ctr] = $$dest[$idx[$ctr]];
547: $ctr++;
548: }
549: &random_set_seed(@oldseed);
550: return @output;
551: } else {
552: my $num = scalar(@$source);
553: my @idx = &math_random_permuted_index($num);
554: my $ctr = 0;
555: my $tot = $num;
556: $tot = $destct if $destct < $num;
557: if (ref($$dest[0])) {
558: while ($ctr < $tot) {
559: ${$$dest[$ctr]} = $$source[$idx[$ctr]];
560: $ctr++;
561: }
562: } else {
563: while ($ctr < $tot) {
564: $$dest[$ctr] = $$source[$idx[$ctr]];
565: $ctr++;
566: }
567: }
568: }
569: &random_set_seed(@seed);
570: return '';
571: }
572:
573: sub rmap {
574: my ($phrase,$dest,$source)=@_;
575: my @oldseed=&random_get_seed();
576: my @seed = &random_seed_from_phrase($phrase);
577: &random_set_seed(@seed);
578: my $destct = scalar(@$dest);
579: if (!$source) {
580: my @idx = &math_random_permuted_index($destct);
581: my $ctr = 0;
582: my @r_idx;
583: while ($ctr < $destct) {
584: $r_idx[$idx[$ctr]] = $ctr;
585: $ctr++;
586: }
587: my @output;
588: $ctr = 0;
589: while ($ctr < $destct) {
590: $output[$ctr] = $$dest[$r_idx[$ctr]];
591: $ctr++;
592: }
593: &random_set_seed(@oldseed);
594: return @output;
595: } else {
596: my $num = scalar(@$source);
597: my @idx = &math_random_permuted_index($num);
598: my $ctr = 0;
599: my $tot = $num;
600: $tot = $destct if $destct < $num;
601: my @r_idx;
602: while ($ctr < $tot) {
603: $r_idx[$idx[$ctr]] = $ctr;
604: $ctr++;
605: }
606: $ctr = 0;
607: if (ref($$dest[0])) {
608: while ($ctr < $tot) {
609: ${$$dest[$ctr]} = $$source[$r_idx[$ctr]];
610: $ctr++;
611: }
612: } else {
613: while ($ctr < $tot) {
614: $$dest[$ctr] = $$source[$r_idx[$ctr]];
615: $ctr++;
616: }
617: }
618: }
619: &random_set_seed(@oldseed);
620: return '';
621: }
622:
623: sub capa_id { return }
624:
625: sub problem { return }
626:
627: sub name{
628: my $fullname = &EXT('environment.lastname').', '.&EXT('environment.firstname').' '.&EXT('environment.middlename');
629: $fullname = "" if $fullname eq ", ";
630: $fullname =~ s/\%2d/-/g;
631: return $fullname;
632: }
633:
634: sub student_number {
635: my $id = &EXT('environment.id');
636: $id = '' if $id eq "";
637: return $id;
638: }
639:
640: sub class {
641: my $course = &EXT('course.description');
642: $course = '' if $course eq "";
643: return $course;
644: }
645:
646: sub sec {
647: my $sec = &EXT('request.course.sec');
648: $sec = '' if $sec eq "";
649: return $sec;
650: }
651:
652: sub open_date {
653: my @dc = split(/\s+/,localtime(&EXT('resource.0.opendate')));
654: return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
655: my @hm = split(/:/,$dc[3]);
656: my $ampm = " am";
657: if ($hm[0] > 12) {
658: $hm[0]-=12;
659: $ampm = " pm";
660: }
661: return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
662: }
663:
664: sub due_date {
665: my @dc = split(/\s+/,localtime(&EXT('resource.0.duedate')));
666: return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
667: my @hm = split(/:/,$dc[3]);
668: my $ampm = " am";
669: if ($hm[0] > 12) {
670: $hm[0]-=12;
671: $ampm = " pm";
672: }
673: return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
674: # return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$dc[3];
675: }
676:
677: sub answer_date {
678: my @dc = split(/\s+/,localtime(&EXT('resource.0.answerdate')));
679: return '' if ($dc[0] eq "Wed" and $dc[2] == 31 and $dc[4] == 1969);
680: my @hm = split(/:/,$dc[3]);
681: my $ampm = " am";
682: if ($hm[0] > 12) {
683: $hm[0]-=12;
684: $ampm = " pm";
685: }
686: return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$hm[0].':'.$hm[1].$ampm;
687: # return $dc[0].', '.$dc[1].' '.$dc[2].', '.$dc[4].' at '.$dc[3];
688: }
689:
690: sub array_moments {
691: my @input=@_;
692: my (@output,$N);
693: $N=scalar (@input);
694: $output[0]=$N;
695: if ($N <= 1) {
696: $output[1]=$input[0];
697: $output[1]="Input array not defined" if ($N == 0);
698: $output[2]="variance undefined for N<=1";
699: $output[3]="skewness undefined for N<=1";
700: $output[4]="kurtosis undefined for N<=1";
701: return @output;
702: }
703: my $sum=0;
704: foreach my $line (@input) {
705: $sum+=$line;
706: }
707: $output[1] = $sum/$N;
708: my ($x,$sdev,$var,$skew,$kurt) = 0;
709: foreach my $line (@input) {
710: $x=$line-$output[1];
711: $var+=$x**2;
712: $skew+=$x**3;
713: $kurt+=$x**4;
714: }
715: $output[2]=$var/($N-1);
716: $sdev=sqrt($output[2]);
717: if ($sdev == 0) {
718: $output[3]="inf-variance=0";
719: $output[4]="inf-variance=0";
720: return @output;
721: }
722: $output[3]=$skew/($sdev**3*$N);
723: $output[4]=$kurt/($sdev**4*$N)-3;
724: return @output;
725: }
726:
727: sub choose {
728: my $num = $_[0];
729: return $_[$num];
730: }
731:
732: # expiremental idea
733: sub proper_path {
734: my ($path)=@_;
735: if ( $external::target eq "tex" ) {
736: return '/home/httpd/html'.$path;
737: } else {
738: return $path;
739: }
740: }
741:
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