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- added documentation on <m>

1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2: <html> 3: <head> 4: <title>LON-CAPA Homework System</title> 5: </head> 6: 7: <body bgcolor="white"> 8: <h1>LON-CAPA Homework System</h1> 9: 10: <h2>Tags</h2> 11: <ul> 12: <li> 13: Response tags 14: 15: Arguments for all response tags 16: 17: <ul> 18: <li> 19: ID, if this isn't set it will be set during 20: the publication step. It is used to assign parameters names 21: in a way that can be tracked if an instructor modifies 22: things by hand. 23: </li> 24: <li> 25: name optional, if set, it will be used by the 26: resource assembly tool when one is modifying parameters. 27: </li> 28: </ul> 29: 30: Implemented response tags 31: 32: <ul> 33: <li> 34: <responseparam> if it appears it should be 35: inside of a <*response> tag, defines an externally 36: adjustable parameter for this question. Arguments: 37: <ul> 38: <li> 39: default required, specifies a default value for 40: the parameter 41: </li> 42: <li> 43: name required, specifies an internal name for 44: the parameter 45: </li> 46: <li> 47: type required specifies the type of parameter, 48: one of "tolerance", "int", "float", "string", "date" 49: (configuration of paramters is handled by 50: lonparmset.pm and parameter.html) 51: </li> 52: <li> 53: description a string describing the parameter, 54: this is what is used to talk about a parameter outside 55: of a problem 56: </li> 57: </ul> 58: </li> 59: <li> 60: <numericalresponse> implements a numerical 61: answer, it needs an internal <textline> for 62: the response to go in. It checks all styles of numerical 63: supported in CAPA. Possible args are: 64: <ul> 65: <li>answer required, specifies the correct answer, may be either a perl list or scalar</li> 66: <li>units optional, specifies unit of correct answer, CAPA style</li> 67: </ul> 68: </li> 69: <li> 70: <stringresponse> implements a string answer, 71: it needs an internal <textline> for the 72: response to go in. It can check the string for either case 73: or order. 74: <ul> 75: <li>answer required, specifies the correct answer, may be either a perl list or scalar</li> 76: <li>type optional, CAPA style str args, cs/ci/mc 77: <ul> 78: <li>cs - case senesitive, order important</li> 79: <li>ci - case insenesitive, order important</li> 80: <li>mc - case insenesitive, order unimportant</li> 81: </ul> 82: </li> 83: </ul> 84: <li> 85: <essayresponse> implements a ungraded large 86: text response, it need an internal <textarea> 87: for the response to go in. 88: </li> 89: <li> 90: <imageresponse> implements a image click 91: style image submission, uses the foil structure tags <a 92: href="#foil">below</a>. Additional tags that should appear 93: in a <foil> are: 94: <ul> 95: <li><image> required, the contained text 96: specifies a published graphical resource that is the 97: image used, should only appear once per foil</li> 98: <li><rectangle> required, the contained text 99: specifies a rectangular area that is correct, should 100: look like (1,2)-(3,4), at least 1 required</li> 101: <li><text> required, the contained text is 102: printed on top of the image.</li> 103: </ul> 104: </li> 105: <li> 106: <optionresponse> implements a "select from 107: these choices" style question, the choices are specified 108: by the instructor, it uses the foil structure tags <a 109: href="#foil">below</a> with this additional args: 110: <ul> 111: <li> 112: <foilgroup> is required to have 113: options which should be a perl list of possible 114: options for the student. 115: </li> 116: </ul> 117: </li> 118: <li> 119: <radiobuttonresponse> implements a true / false 120: style question with 1 correct answer.it uses the foil 121: structure tags <a href="#foil">below</a> but the 122: value of a <foil>can only be "true" or 123: "false" or "unused" 124: </li> 125: <li> 126: <dataresponse> implements a straight data 127: storage entry idea, needs and interveing input tag like 128: <textline> to work correctly. 129: Arguments: 130: <ul> 131: <li> 132: name internal name for the value, it will have 133: the part id and respose id added on to it 134: </li> 135: <li> 136: type type of data stored in this response 137: field, should be one of the types supported by 138: parameter.html 139: </li> 140: <li> 141: display a string that will be used to describe 142: the field when interfacing with humans 143: </li> 144: </ul> 145: <li> 146: </ul> 147: <li> 148: <a name="foil">Foil Structure Tags</a> 149: 150: All tags that implement a foil structure have an optional 151: arg of max that controls the maximum number of total 152: foils to show. 153: 154: <ul> 155: <li> 156: <foilgroup> required, must be the tag that 157: surrounds all foil definitions 158: </li> 159: <li> 160: <foil> required, all data inside is a possible foil 161: </li> 162: <li> 163: <conceptgroup> optional, surrounds a 164: collection of <foil>, when a problem is displayed 165: only one of the contained <foil>is selected for 166: display. It receives one required argument 167: concept. 168: </li> 169: </ul> 170: </li> 171: <li> 172: Hint structure 173: 174: All of these tags must appear inside a <*response> tag. 175: 176: <ul> 177: <li> 178: <hintgroup> Tag that surrounds all of a hint. 179: </li> 180: <li> 181: <hintpart> required, Tag to implement 182: conditional hints. It has a required argument 183: on. When a <*hint> tag named the same as the 184: value the on attribute evaluates to be correct the 185: <hintpart> will show. If no other <hintpart> 186: are to show then all hintparts with a on of 187: "default" will show 188: </li> 189: <li> 190: <numericalhint> has all the arguments that 191: <numericalresponse>, does and the required attribute 192: name which should be set to the value of which 193: <hintpart> will be shown. 194: </li> 195: </ul> 196: </li> 197: <li> 198: Input Tags 199: 200: This group of tags implement a mechanism for getting data 201: for students, they will usually be used by a 202: <*response>. 203: 204: <ul> 205: <li> 206: <textarea> creates a Large text input box, If 207: data appears between the start and end tags, the data will 208: appear i the textarea if the student has not yet made a 209: submission. Additionally it takes two arguments rows 210: and cols which control the height and width of the 211: area respectively. It defaults to 10 and 80. 212: </li> 213: <li> 214: <textline> creates a single line of input 215: element, it accepts 1 argument size which controls 216: the width on the textline, it defaults to 20. 217: </li> 218: </ul> 219: </li> 220: <li> 221: Output Tags 222: 223: This group of tags generate useful pieces of output. 224: 225: <ul> 226: <li> 227: <displayduedate> this will insert the current 228: duedate if one is set into the document. It is generated 229: to be inside a table of 1x1 elements 230: </li> 231: <li> 232: <displaytitle> this will insert the title of 233: the problem from the metadata of the problem 234: </li> 235: <li> 236: <window> the text in between is put in a 237: popup javascript window 238: </li> 239: <li> 240: <m> the inside text is LaTeX, and is 241: converted to HTML (or MathML) on the fly, if the argument 242: eval is set to "on" the intervening text will have 243: a perl var expansion done to it before being converted. 244: </li> 245: </ul> 246: </li> 247: <li> 248: Scripting 249: 250: These tags allow the document to behave programatically 251: 252: <ul> 253: <li> 254: <display> the intervening perl script is 255: evaluated in the safe space and the return value of the 256: script replaces the entire tag 257: </li> 258: <li> 259: <import> causes the parse to read in the file 260: named in the body of the tag and parse it as if the entire 261: text of the file had existed at location of the tag 262: </li> 263: <li> 264: <parserlib> the enclosed filename contains 265: definitions for new tags 266: </li> 267: <li> 268: <script> if the argument type is set 269: to "loncapa/perl" the enclosed data is a perl script which 270: is evaluated inside the perl Safe space. The return value 271: of the script is ignored. 272: </li> 273: <li> 274: <scriptlib> the enclosed filename contains 275: perl code to run in the safe space 276: </li> 277: <li> 278: <block> has a required argument 279: condition that is evaluated, it the condition is 280: true everything inside the tag is evaluated, if it is false 281: everything inside the block tag is skipped 282: </li> 283: <li> 284: <notsolved> everything inside the tag is 285: skipped if the problem is "solved" 286: </li> 287: <li> 288: <postanswerdate> everything inside the tag is 289: skipped if the problem is before the answer date 290: </li> 291: <li> 292: <preduedate> everything inside the tag is 293: skipped if the problem is after the due date 294: </li> 295: <li> 296: <randomlist> the enclosed tags are parsed in 297: a stable random order 298: </li> 299: <li> 300: <solved> everything inside the tag is 301: skipped if the problem is "not solved" 302: </li> 303: <li> 304: <while> implements a while loop, required 305: argument condition is a perl scriptlet that when 306: evaluated results in a true or false value, on true the 307: entirety of the text between the whiles is parsed. The 308: condition is tested again, etc. If false it goes to the 309: next node in the parse. 310: </li> 311: </ul> 312: </li> 313: <li> 314: Structure Tags 315: 316: These tags give the problem a structure and take care of the 317: recording of data and giving the student messages. 318: 319: <ul> 320: <li> 321: <problem> must be the first tag in the file, 322: this tag sets up the header of the webpage and generates 323: the submit buttons, it also handles due dates properly 324: </li> 325: <li> 326: <part> must be below <problem> if it is 327: going to be used. It does many of the same tasks as 328: <problem> but allows multiple separate problems to 329: exist in a single file. 330: </li> 331: <li> 332: <startouttext><endouttext> these 333: tags are somewhat special, they must have no internal text 334: and occur in pairs. Their use is to mark up the problem so 335: the web editor knows what sections should be edited in a 336: plain text block on the web. 337: </li> 338: </ul> 339: </li> 340: </ul> 341: <h2><script> Functions</h2> 342: 343: A list of functions that have been written that are available in 344: the Safe space scripting environment inside a problem. 345: 346: <ul> 347: <li>sin(x), cos(x), tan(x)</li> 348: <li>asin(x), acos(x), atan(x), atan2(y,x)</li> 349: <li>log(x), log10(x)</li> 350: <li>exp(), pow(x,y), sqrt(x)</li> 351: <li>abs(x), sgn(x)</li> 352: <li>erf(x), erfc(x)</li> 353: <li>ceil(x), floor(x)</li> 354: <li>min(...), max(...)</li> 355: <li>factorial(n)</li> 356: <li>N%M</li> 357: <li>sinh(x), cosh(x), tanh(x)</li> 358: <li>asinh(x), acosh(x), atanh(x)</li> 359: <li>roundto(x,n)</li> 360: <li>web("a","b","c") or web(a,b,c)</li> 361: <li>html("a") or html(a)</li> 362: <li>j0(x), j1(x), jn(n,x), jv(y,x)</li> 363: <li>y0(x), y1(x), yn(n,x), yv(y,x)</li> 364: <li>random</li> 365: <li>choose</li> 366: <li>tex("a","b") or tex(a,b)</li> 367: <li>var_in_tex(a)</li> 368: <li>to_string(x), to_string(x,y)</li> 369: <li>class(), section()</li> 370: <li>name(), student_number()</li> 371: <li>open_date(), due_date(), answer_date()</li> 372: <li>sub_string()</li> 373: <li>array_moments(array)</li> 374: <li>format(x,y)</li> 375: <li>map(...)</li> 376: <li>caparesponse_check</li> 377: <li>caparesponse_check_list</li> 378: </ul> 379:  383: 384: Detailed descriptions of each function and comparison with CAPA. 385: 386: 387: <table border=1> 388: <tr> 389: <td valign="top">CAPA Functions</b</td> 390: <td valign="top">LON-CAPA</b</td> 391: <td valign="top">Descriptions</b</td> 392: <td valign="top">Differences (if any)</b</td> 393: </tr> 394: 395: <tr> 396: <td valign="top">sin(x), cos(x), tan(x)</td> 397: <td valign="top">&sin($x), &cos($x), &tan($x)</td> 398: <td valign="top">Trigonometric functions where x is in radians. $x 399: can be a pure number, i.e., you can call &sin(3.1415)</td> 400: <td valign="top">&nbsp</td> 401: </tr> 402: 403: <tr> 404: <td valign="top">asin(x), acos(x), atan(x), atan2(y,x)</td> 405: <td valign="top">&asin($x), &acos($x), &atan($x), &atan2($y,$x)</td> 406: <td valign="top">Inverse trigonometric functions. Return value is 407: in radians. For asin and acos the value of x must be between -1 and 1. 408: The atan2 returns a value between -pi and pi the sign of which is determined 409: by y. $x and $y can be pure numbers</td> 410: <td valign="top"> </td> 411: </tr> 412: 413: <tr> 414: <td valign="top">log(x), log10(x)</td> 415: <td valign="top">&log($x), &log10($x)</td> 416: <td valign="top">Natural and base-10 logarithm. $x can be a pure number</td> 417: <td valign="top"> </td> 418: </tr> 419: 420: <tr> 421: <td valign="top">exp(x), pow(x,y), sqrt(x)</td> 422: <td valign="top">&exp($x), &pow($x,$y), &sqrt($x)</td> 423: <td valign="top">Exponential, power and square root, i.e.,ex, xy and /x. $x and $y can be pure numbers</td> 424: 425: <td valign="top"> </td> 426: </tr> 427: 428: <tr> 429: <td valign="top">abs(x), sgn(x)</td> 430: <td valign="top">&abs($x), &sgn($x)</td> 431: <td valign="top">Abs takes the absolute value of x while sgn(x) returns 432: 1, 0 or -1 depending on the value of x. For x>0, sgn(x) = 1, for x=0, sgn(x) 433: = 0 and for x<0, sgn(x) = -1. $x can be a pure number</td> 434: <td valign="top"> </td> 435: </tr> 436: 437: <tr> 438: <td valign="top">erf(x), erfc(x)</td> 439: <td valign="top">&erf($x), &erfc($x)</td> 440: <td valign="top">Error function.  erf = 2/sqrt(pi) integral (0,x) et-sq and erfx(x) = 1.0 - erf(x).  $x can be a pure number</td> 441: <td valign="top"> </td> 442: </tr> 443: 444: <tr> 445: <td valign="top">ceil(x), floor(x)</td> 446: <td valign="top">&ceil($x), &floor($x)</td> 447: <td valign="top">Ceil function returns an integer rounded up whereas 448: floor function returns and integer rounded down. If x is an integer than 449: it returns the value of the integer. $x can be a pure number</td> 450: <td valign="top"> </td> 451: </tr> 452: 453: <tr> 454: <td valign="top">min(...), max(...)</td> 455: <td valign="top">&min(...), &max(...)</td> 456: <td valign="top">Returns the minimum/ maximum value of a list of 457: arguments if the arguments are numbers. If the arguments are strings then 458: it returns a string sorted according to the ASCII codes</td> 459: <td valign="top"> </td> 460: </tr> 461: 462: <tr> 463: <td valign="top">factorial(n)</td> 464: <td valign="top">&factorial($n)</td> 465: <td valign="top">Argument (n) must be an integer else it will round 466: down. The largest value for n is 170. $n can be a pure number</td> 467: <td valign="top"> </td> 468: </tr> 469: 470: <tr> 471: <td valign="top">N%M</td> 472: <td valign="top">$N%$M</td> 473: 474: <td valign="top">N and M are integers and returns the remainder (in 475: integer) of N/M. $N and $M can be pure numbers</td> 476: <td valign="top"> </td> 477: </tr> 478: 479: <tr> 480: <td valign="top">sinh(x), cosh(x), tanh(x)</td> 481: <td valign="top">&sinh($x), &cosh($x), &tanh($x)</td> 482: <td valign="top">Hyperbolic functions. $x can be a pure number</td> 483: <td valign="top"> </td> 484: </tr> 485: 486: <tr> 487: <td valign="top">asinh(x), acosh(x), atanh(x)</td> 488: <td valign="top">&asinh($x), &acosh($x), &atanh($x)</td> 489: <td valign="top">Inverse hyperbolic functions. $x can be a pure number</td> 490: <td valign="top"> </td> 491: </tr> 492: 493: <tr> 494: <td valign="top">/DIS($x,"nn")</td> 495: <td valign="top">&format($x,"nn")</td> 496: <td valign="top">Display or format $x as nn where nn is nF or nE and n is an integer.</td> 497: <td valign="top"> The difference is obvious.</td> 498: </tr> 499: 500: <tr> 501: <td valign="top">roundto(x,n)</td> 502: <td valign="top">&roundto($x,$n)</td> 503: <td valign="top">Rounds a real number to n decimal points. $x and 504: $n can be pure numbers</td> 505: <td valign="top"> </td> 506: </tr> 507: 508: <tr> 509: <td valign="top">web("a","b","c") or web(a,b,c)</td> 510: <td valign="top">&web("a","b","c") or &web($a,$b,$c)</td> 511: <td valign="top">Returns either a, b or c depending on the output 512: medium. a is for plain ASCII, b for tex output and c for html output</td> 513: <td valign="top">&nbsp</td> 514: </tr> 515: 516: <tr> 517: <td valign="top">html("a") or html(a)</td> 518: <td valign="top">&html("a") or &html($a)</td> 519: <td valign="top">Output only if the output mode chosen is in html 520: format</td> 521: <td valign="top"> </td> 522: </tr> 523: 524: <tr> 525: <td valign="top">jn(m,x)</td> 526: <td valign="top">&j0($x), &j1($x), &jn($m,$x), &jv($y,$x)</td> 527: <td valign="top">Bessel functions of the first kind with orders 0, 528: 1 and m respectively. For jn(m,x), m must be an integer whereas for jv(y,x), 529: y is real. $x can be a pure number. $m must be an integer and can be a 530: pure integer number. $y can be a pure real number</td> 531: <td valign="top">In CAPA, j0, j1 and jn are contained in one function, 532: jn(m,x) where m takes the value of 0, 1 or 2. jv(y,x) is new to LON-CAPA.</td> 533: </tr> 534: 535: <tr> 536: <td valign="top">yn(m,x)</td> 537: <td valign="top">&y0($x), &y1($x), &yn($m,$x), &yv($y,$x)</td> 538: <td valign="top">Bessel functions of the second kind with orders 539: 0, 1 and m respectively. For yn(m,x), m must be an integer whereas for 540: yv(y,x), y is real. $x can be a pure number. $m must be an integer and 541: can be a pure integer number. $y can be a pure real number</td> 542: <td valign="top">In CAPA, y0, y1 and yn are contained in one function, 543: yn(m,x) where m takes the value of 0, 1 or 2. yv(y,x) is new to LON-CAPA.</td> 544: </tr> 545: 546: <tr> 547: <td valign="top">random(l,u,d)</td> 548: <td valign="top">&random($l,$u,$d)</td> 549: <td valign="top">Returns a uniformly distributed random number between 550: the lower bound, l and upper bound, u in steps of d. $l, $u and $d can 551: be pure numbers</td> 552: <td valign="top">In CAPA, all the 3 arguments must be of the same 553: type. However, now you can mix the type</td> 554: </tr> 555: 556: <tr> 557: <td valign="top">choose(i,...)</td> 558: <td valign="top">&choose($i,...)</td> 559: <td valign="top">Choose the ith item from the argument list. i must 560: be an integer greater than 0 and the value of i should not exceed the number 561: of items. $i can be a pure integer</td> 562: <td valign="top"> </td> 563: </tr> 564: 565: <tr> 566: <td valign="top">/MAP(seed;w,x,y,z;a,b,c,d)</td> 567: <td valign="top">Option 1 - &map($seed,[\$w,\$x,\$y,\$z],[$a,$b,$c,$d]) or 568: Option 2 - &map($seed,\@mappedArray,[$a,$b,$c,$d]) 569: Option 3 - @mappedArray = &map($seed,[$a,$b,$c,$d]) 570: Option 4 - ($w,$x,$y,$z) = &map($seed,\@a) 571: where $a='A' 572: $b='B' 573: $c='B' 574: $d='B' 575: $w, $x, $y, and $z are variables</td> 576: <td valign="top">Assigns to the variables $w, $x, $y and $z the values of the 577: $a, $b, $c and $c (A, B, C and D). The precise value for $w .. depends 578: on the seed. (Option 1 of calling map). 579: In option 2, the values of $a, $b .. are mapped into the array, @mappedArray. The two 580: options illustrate the different grouping. Options 3 and 4 give a consistent 581: way (with other functions) of mapping the items. For each option, the group can 582: be passed as an array, for example, [$a,$b,$c,$d] => \@a.</td> 583: <td valign="top">In CAPA, the arguments are divided into three groups separated 584: by a semicolon ;. In LON-CAPA, the separation is done by using [] brackets or 585: using an array @a. Note the backslash (\) before the arguments in the 586: second and third groups.</td> 587: </tr> 588: 589: 590: <tr> 591: <td valign="top">rmap(seed;a,b,c,d;w,x,y,z)</td> 592: <td valign="top">Option 1 - &rmap($seed,[\$w,\$x,\$y,\$z],[$a,$b,$c,$d]) or 593: Option 2 - &rmap($seed,\@rmappedArray,[$a,$b,$c,$d]) 594: Option 3 - @rmapped_array = &rmap($seed,[$a,$b,$c,$d]) 595: Option 4 - ($w,$x,$y,$z) = &rmap($seed,\@a) 596: where $a='A' 597: $b='B' 598: $c='B' 599: $d='B' 600: $w, $x, $y, and $z are variables</td> 601: <td valign="top">The rmap functions does the reverse action of map if the same seed 602: is used in calling map and rmap. </td> 603: <td valign="top">In CAPA, the arguments are divided into 604: three groups separated by a semicolon ;. In LON-CAPA, the 605: separation is done by using [] brackets (with create an 606: unamed vector reference) or using an array @a. Note the 607: backslash (\) before the arguments in the second and 608: third groups (Which cause Perl to send to variable 609: locations rather than the variable values, similar to a C 610: pointer).</td> 611: </tr> 612: 613: <tr> 614: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 615: <td valign="top">$a=&xmlparse($string) </td> 616: <td valign="top">Runs the internal parser over the 617: argument parsing for display. Warning This will 618: result in different strings in different targets. Don't use 619: the results of this function as an answer.</td> 620: <td valign="top">New to LON-CAPA</td> 621: </tr> 622: 623: <tr> 624: <td valign="top">tex(a,b), tex("a","b")</td> 625: <td valign="top">&tex($a,$b), &tex("a","b")</td> 626: <td valign="top">Returns a if the output mode is in tex otherwise 627: returns b</td> 628: <td valign="top"> </td> 629: </tr> 630: 631: <tr> 632: <td valign="top">var_in_tex(a)</td> 633: <td valign="top">&var_in_tex($a)</td> 634: <td valign="top">Equivalent to tex("a","")</td> 635: <td valign="top"> </td> 636: </tr> 637: 638: <tr> 639: <td valign="top">to_string(x), to_string(x,y)</td> 640: <td valign="top">&to_string($x), &to_string($x,$y)</td> 641: <td valign="top">If x is an integer, returns a string. If x is real 642: than the output is a string with format given by y. For example, if x = 643: 12.3456, &to_string(x,".3F") = 12.345 and &to_string(x,".3E") = 644: 1.234E+01.</td> 645: <td valign="top"> </td> 646: </tr> 647: 648: <tr> 649: <td valign="top">capa_id(), class(), section(), set(), problem()</td> 650: <td valign="top">&class(), &section()</td> 651: <td valign="top">Returns null string, class descriptive name, section 652: number, set number and null string.</td> 653: <td valign="top">capa_id(), set() and problem() are no longer used. 654: Currently, they return a null value.</td> 655: </tr> 656: 657: <tr> 658: <td valign="top">name(), student_number()</td> 659: <td valign="top">&name(), &student_number()</td> 660: <td valign="top">Return the full name in the following format: lastname, 661: firstname initial. Student_number returns the student 9-alphanumeric string. 662: If undefined, the functions return null.</td> 663: <td valign="top"> </td> 664: </tr> 665: 666: <tr> 667: <td valign="top">open_date(), due_date(), answer_date()</td> 668: <td valign="top">&open_date(), &due_date(), &answer_date()</td> 669: <td valign="top">Problem open date, due date and answer date. The 670: time is also included in 24-hr format.</td> 671: <td valign="top">Output format for time is changed slightly. If pass 672: noon, it displays ..pm else it displays ..am. So 23:59 is displayed as 673: 11:59 pm.</td> 674: </tr> 675: 676: <tr> 677: <td valign="top">get_seed(), set_seed()</td> 678: <td valign="top">Not implemented</td> 679: <td valign="top">Get and set the random seed.</td> 680: <td valign="top"> </td> 681: </tr> 682: 683: <tr> 684: <td valign="top">sub_string(a,b,c)</td> 685: <td valign="top">&sub_string($a,$b,$c) perl  substr function. 686: However, note the differences</td> 687: <td valign="top">Retrieve a portion of string a starting from b and 688: length c. For example,  $a = "Welcome to LON-CAPA"; 689: $result=&sub_string($a,4,4); then $result is "come"</td> 690: <td valign="top">Perl intrinsic function, substr(string,b,c) starts 691: counting from 0 (as opposed to 1). In the example to the left, substr($a,4,4) 692: returns "ome ".</td> 693: </tr> 694: 695: <tr> 696: <td valign="top">array[xx]</td> 697: <td valign="top">@arrayname Array is intrinsic in perl. 698: To access a specific element use $arrayname[$n] where $n 699: is the $n+1 element since the array count starts from 0</td> 700: <td valign="top">"xx" can be a variable or a calculation.</td> 701: <td valign="top">In LON-CAPA, an array is defined by @arrayname. 702: It is not necessary to specify the dimension of the array. </td> 703: </tr> 704: 705: <tr> 706: <td valign="top">array_moments(B,A)</td> 707: <td valign="top">@B=&array_moments(@A)</td> 708: <td valign="top">Evaluates the moments of an array A and place the 709: result in array B[i] where i = 0 to 4. The contents of B are as follows: 710: B[0] = number of elements, B[1] = mean, B[2] = variance, B[3] = skewness 711: and B[4] = kurtosis.</td> 712: <td valign="top">In CAPA, the moments are passed as an array in the first argument whereas 713: in LON-CAPA, the array containing the moments are set equal to the function.</td> 714: </tr> 715: 716: <tr> 717: <td valign="top">array_max(Name), array_min(Name)</td> 718: <td valign="top">&min(@Name), &max(@Name)</td> 719: <td valign="top">In LON-CAPA to find the maximum value of an array, use 720: &max(@arrayname)  and to find the minimum value of an array, use 721: &min(@arrayname)</td> 722: <td valign="top">Combined with the min and max functions defined 723: earlier.</td> 724: </tr> 725: 726: <tr> 727: <td valign="top">init_array(Name)</td> 728: <td valign="top">undef @name</td> 729: <td valign="top">To destroy the contents of an array, use</td> 730: <td valign="top">Use perl intrinsic undef function.</td> 731: </tr> 732: <tr> 733: <td valign="top">random_normal (return_array,item_cnt,seed,av,std_dev)</td> 734: <td valign="top">@return_array=&random_normal ($item_cnt,$seed,$av,$std_dev)</td> 735: <td valign="top">Generate $item_cnt deviates of normal distribution of average $av and 736: standard deviation $std_dev. The distribution is generated from seed $seed</td> 737: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 738: the results are set equal to the function.</td> 739: </tr> 740: <tr> 741: <td valign="top">random_beta (return_array,item_cnt,seed,aa,bb)</td> 742: <td valign="top">@return_array=&random_beta ($item_cnt,$seed,$aa,$bb) 743: NOTE: Both $aa and $bb MUST be greater than 1.0E-37.</td> 744: <td valign="top">Generate $item_cnt deviates of beta distribution. 745: The density of beta is: 746: X^($aa-1) *(1-X)^($bb-1) /B($aa,$bb) for 0<X<1.</td> 747: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 748: the results are set equal to the function.</td> 749: </tr> 750: <tr> 751: <td valign="top">random_gamma (return_array,item_cnt,seed,a,r)</td> 752: <td valign="top">@return_array=&random_gamma ($item_cnt,$seed,$a,$r) 753: NOTE: Both $a and $r MUST be positive.</td> 754: <td valign="top">Generate $item_cnt deviates of gamma distribution. 755: The density of gamma is: 756: ($a**$r)/gamma($r) * X**($r-1) * exp(-$a*X).</td> 757: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 758: the results are set equal to the function.</td> 759: </tr> 760: <tr> 761: <td valign="top">random_exponential (return_array,item_cnt,seed,av)</td> 762: <td valign="top">@return_array=&random_exponential ($item_cnt,$seed,$av) 763: NOTE: $av MUST be non-negative.</td> 764: <td valign="top">Generate $item_cnt deviates of exponential distribution. </td> 765: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 766: the results are set equal to the function.</td> 767: </tr> 768: <tr> 769: <td valign="top">random_poisson (return_array,item_cnt,seed,mu)</td> 770: <td valign="top">@return_array=&random_poisson ($item_cnt,$seed,$mu) 771: NOTE: $mu MUST be non-negative.</td> 772: <td valign="top">Generate $item_cnt deviates of poisson distribution. </td> 773: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 774: the results are set equal to the function.</td> 775: </tr> 776: <tr> 777: <td valign="top">random_chi (return_array,item_cnt,seed,df)</td> 778: <td valign="top">@return_array=&random_chi ($item_cnt,$seed,$df) 779: NOTE: $df MUST be positive.</td> 780: <td valign="top">Generate $item_cnt deviates of chi_square distribution with $df 781: degrees of freedom. </td> 782: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 783: the results are set equal to the function.</td> 784: </tr> 785: <tr> 786: <td valign="top">random_noncentral_chi (return_array,item_cnt,seed,df,nonc)</td> 787: <td valign="top">@return_array=&random_noncentral_chi ($item_cnt,$seed,$df,$nonc) 788: NOTE: $df MUST be at least 1 and $nonc MUST be non-negative.</td> 789: <td valign="top">Generate $item_cnt deviates of noncentral_chi_square 790: distribution with $df 791: degrees of freedom and noncentrality parameter $nonc. </td> 792: <td valign="top">In CAPA the results are passed as the first argument whereas in LON-CAPA 793: the results are set equal to the function.</td> 794: </tr> 795: <tr> 796: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 797: <td valign="top">@return_array=&random_f ($item_cnt,$seed,$dfn,$dfd) 798: NOTE: Both $dfn and $dfd MUST be positive.</td> 799: <td valign="top">Generate $item_cnt deviates of F (variance ratio) distribution with 800: degrees of freedom $dfn (numerator) and $dfd (denominator). </td> 801: <td valign="top">New to LON-CAPA</td> 802: </tr> 803: <tr> 804: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 805: <td valign="top">@return_array=&random_noncentral_f ($item_cnt,$seed,$dfn,$dfd,$nonc) 806: NOTE: $dfn must be at least 1, $dfd MUST be positive, and $nonc must 807: be non-negative.</td> 808: <td valign="top">Generate $item_cnt deviates of noncentral F (variance ratio) 809: distribution with degrees of freedom $dfn (numerator) and $dfd (denominator). 810: $nonc is the noncentrality parameter. </td> 811: <td valign="top">New to LON-CAPA</td> 812: </tr> 813: <tr> 814: <td valign="top">NOT DOCUMENTED IN CAPA</td> 815: <td valign="top">@return_array=&random_multivariate_normal ($item_cnt,$seed,\@mean,\@covar) 816: NOTE: @mean should be of length p array of real numbers. @covar should be a length 817: p array of references to length p arrays of real numbers (i.e. a p by p matrix.</td> 818: <td valign="top">Generate $item_cnt deviates of multivariate_normal distribution with 819: mean vector @mean and variance-covariance matrix. </td> 820: <td valign="top">Note the backslash before the @mean and @covar arrays.</td> 821: </tr> 822: <tr> 823: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 824: <td valign="top">@return_array=&random_multinomial ($item_cnt,$seed,@p) 825: NOTE: $item_cnt is rounded with int() and the result must be non-negative. 826: The number of elements in @p must be at least 2.</td> 827: <td valign="top">Returns single observation from multinomial distribution with 828: $item_cnt events classified into as many categories as the length of @p. 829: The probability of an event being classified into category i is given by 830: ith element of @p. The observation is an array with length equal to @p, so 831: when called in a scalar context it returns the length of @p. The sum of the 832: elements of the obervation is equal to $item_cnt.</td> 833: <td valign="top">New to LON-CAPA</td> 834: </tr> 835: <tr> 836: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 837: <td valign="top">@return_array=&random_permutation ($item_cnt,@array) </td> 838: <td valign="top">Returns @array randomly permuted.</td> 839: <td valign="top">New to LON-CAPA</td> 840: </tr> 841: <tr> 842: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 843: <td valign="top">@return_array=&random_uniform ($item_cnt,$seed,$low,$high) 844: NOTE: $low must be less than or equal to $high.</td> 845: <td valign="top">Generate $item_cnt deviates from a uniform distribution. </td> 846: <td valign="top">New to LON-CAPA</td> 847: </tr> 848: <tr> 849: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 850: <td valign="top">@return_array=&random_uniform_integer ($item_cnt,$seed,$low,$high) 851: NOTE: $low and $high are both passed through int(). 852: $low must be less than or equal to $high.</td> 853: <td valign="top">Generate $item_cnt deviates from a uniform distribution in integers. </td> 854: <td valign="top">New to LON-CAPA</td> 855: </tr> 856: <tr> 857: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 858: <td valign="top">@return_array=&random_binomial ($item_cnt,$seed,$nt,$p) 859: NOTE: $nt is rounded using int() and the result must be non-negative. 860: $p must be between 0 and 1 inclusive.</td> 861: <td valign="top">Generate $item_cnt deviates from the binomial distribution with 862: $nt trials and the probabilty of an event in each trial is $p. </td> 863: <td valign="top">New to LON-CAPA</td> 864: </tr> 865: <tr> 866: <td valign="top">NOT IMPLEMENTED IN CAPA</td> 867: <td valign="top">@return_array=&random_negative_binomial ($item_cnt,$seed,$ne,$p) 868: NOTE: $ne is rounded using int() and the result must be positive. 869: $p must be between 0 and 1 exclusive.</td> 870: <td valign="top">Generate an array of $item_cnt outcomes generated from 871: negative binomial distribution with 872: $ne events and the probabilty of an event in each trial is $p. </td> 873: <td valign="top">New to LON-CAPA</td> 874: </tr> 875: </table> 876:  877: 878: <h2><script> Variables</h2> 879: <ul> 880: <li> 881: $external::target - set to the current target the xml parser 882: is parsing for 883: </li> 884: <li> 885: $external::part - set to the id of the current problem 886: <part>; zero if there are now <part> 887: </li> 888: <li> 889: $external::gradestatus - set to the value of the current 890: resource.partid.solved value 891: </li> 892: <li> 893: $external::datestatus - set to the current status of the clock 894: either CLOSED, CAN_ANSWER, CANNOT_ANSWER, or SHOW_ANSWER 895: </li> 896: <li> 897: $external::randomseed - set to the number that was used to 898: seed the random number generator 899: </li> 900: <li>$pi - set to PI </li> 901: <li>$rad2deg - converts radians to degrees </li> 902: <li>$deg2rad - converts degrees to radians </li> 903: </ul> 904: 905: <hr> 906: <address><a href="mailto:albertel@marvin.lite.msu.edu">Guy Albertelli</a></address> 907:  908:  909: Last modified: Fri Dec 7 10:03:55 EST 2001 910:  911: </body> 912: </html>