1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
|
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>GAP (AtlasRep) - Chapter 4: Customizations of the AtlasRep Package</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<meta name="generator" content="GAPDoc2HTML" />
<link rel="stylesheet" type="text/css" href="manual.css" />
<script src="manual.js" type="text/javascript"></script>
<script type="text/javascript">overwriteStyle();</script>
</head>
<body class="chap4" onload="jscontent()">
<div class="chlinktop"><span class="chlink1">Goto Chapter: </span><a href="chap0.html">Top</a> <a href="chap1.html">1</a> <a href="chap2.html">2</a> <a href="chap3.html">3</a> <a href="chap4.html">4</a> <a href="chap5.html">5</a> <a href="chap6.html">6</a> <a href="chap7.html">7</a> <a href="chapBib.html">Bib</a> <a href="chapInd.html">Ind</a> </div>
<div class="chlinkprevnexttop"> <a href="chap0.html">[Top of Book]</a> <a href="chap0.html#contents">[Contents]</a> <a href="chap3.html">[Previous Chapter]</a> <a href="chap5.html">[Next Chapter]</a> </div>
<p id="mathjaxlink" class="pcenter"><a href="chap4_mj.html">[MathJax on]</a></p>
<p><a id="X797694467B534D0E" name="X797694467B534D0E"></a></p>
<div class="ChapSects"><a href="chap4.html#X797694467B534D0E">4 <span class="Heading">Customizations of the <strong class="pkg">AtlasRep</strong> Package</span></a>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap4.html#X7F25ECBA7B675901">4.1 <span class="Heading">Installing the <strong class="pkg">AtlasRep</strong> Package</span></a>
</span>
</div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap4.html#X851A50E6810EF8C5">4.2 <span class="Heading">User Preferences of the <strong class="pkg">AtlasRep</strong> Package</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X7C3293A98577EE68">4.2-1 <span class="Heading">User preference <code class="code">AtlasRepAccessRemoteFiles</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X7C36E9A78021A71A">4.2-2 <span class="Heading">User preference <code class="code">AtlasRepDataDirectory</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X7F21FFBE7F8108E4">4.2-3 <span class="Heading">User preference <code class="code">AtlasRepTOCData</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X8766BE5D7AD6C526">4.2-4 <span class="Heading">User preference <code class="code">CompressDownloadedMeatAxeFiles</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X81AD105979465162">4.2-5 <span class="Heading">User preference <code class="code">FileAccessFunctions</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X85C48D6D81095161">4.2-6 <span class="Heading">User preference <code class="code">AtlasRepLocalServerPath</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X79993585808450FA">4.2-7 <span class="Heading">User preference <code class="code">HowToReadMeatAxeTextFiles</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X7B8F757B85F87936">4.2-8 <span class="Heading">User preference <code class="code">WriteHeaderFormatOfMeatAxeFiles</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X7941C4378261E28A">4.2-9 <span class="Heading">User preference <code class="code">WriteMeatAxeFilesOfMode2</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X877E40DB7A4E36C9">4.2-10 <span class="Heading">User preference <code class="code">BaseOfMeatAxePermutation</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X81F055037F9D3068">4.2-11 <span class="Heading">User preference <code class="code">DisplayFunction</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X862C660878D422FA">4.2-12 <span class="Heading">User preference <code class="code">AtlasRepMarkNonCoreData</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X80958D068147325B">4.2-13 <span class="Heading">User preference <code class="code">DebugFileLoading</code></span></a>
</span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap4.html#X850D135E79EFF3F7">4.2-14 <span class="Heading">User preference <code class="code">AtlasRepJsonFilesAddresses</code></span></a>
</span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap4.html#X7C50F18587ADC3B5">4.3 <span class="Heading">Web Contents for the <strong class="pkg">AtlasRep</strong> Package</span></a>
</span>
</div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap4.html#X7FB64AD37D4620E6">4.4 <span class="Heading">Extending the <strong class="pkg">ATLAS</strong> Database</span></a>
</span>
</div>
</div>
<h3>4 <span class="Heading">Customizations of the <strong class="pkg">AtlasRep</strong> Package</span></h3>
<p><a id="X7F25ECBA7B675901" name="X7F25ECBA7B675901"></a></p>
<h4>4.1 <span class="Heading">Installing the <strong class="pkg">AtlasRep</strong> Package</span></h4>
<p>To install the package, unpack the archive file in a directory in the <code class="file">pkg</code> directory of your local copy of <strong class="pkg">GAP</strong> 4. This might be the <code class="file">pkg</code> directory of the <strong class="pkg">GAP</strong> 4 root directory, see <a href="../../../doc/ref/chap76.html#X82473E4B8756C6CD"><span class="RefLink">Reference: Installing a GAP Package</span></a> for details. It is however also possible to keep an additional <code class="file">pkg</code> directory somewhere else, see Section <a href="../../../doc/ref/chap9.html#X7A4973627A5DB27D"><span class="RefLink">Reference: GAP Root Directories</span></a>. The latter possibility <em>must</em> be chosen if you do not have write access to the <strong class="pkg">GAP</strong> root directory.</p>
<p>If it is likely that you will work offline, it makes sense to install the <q>starter archive</q> that can be downloaded from the package's homepage.</p>
<p>The package consists entirely of <strong class="pkg">GAP</strong> code, no external binaries need to be compiled for the package itself.</p>
<p>After unpacking the package archive, the write permissions for those directories should be checked into which users will download files. Every user can customize these paths via a user preference, see Section <a href="chap4.html#X7C36E9A78021A71A"><span class="RefLink">4.2-2</span></a>, the defaults are the subdirectories <code class="file">data*</code> of the package directory. The recommended permissions under UNIX for the default directories are set as follows.</p>
<div class="example"><pre>
you@unix> chmod 1777 atlasrep/data*
you@unix> ls -ld atlasrep/data*
drwxrwxrwt 3 you you 1024 Apr 12 12:34 dataext
drwxrwxrwt 3 you you 1024 Apr 12 12:34 datagens
drwxrwxrwt 3 you you 1024 Apr 12 12:34 datapkg
drwxrwxrwt 3 you you 1024 Apr 12 12:34 dataword
</pre></div>
<p>For checking the installation of the package, you should start <strong class="pkg">GAP</strong> and call</p>
<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">ReadPackage( "atlasrep", "tst/testinst.g" );</span>
</pre></div>
<p>If the installation is o.k. then the <strong class="pkg">GAP</strong> prompt appears without anything else being printed; otherwise the output lines tell you what should be changed.</p>
<p>PDF, HTML, and text versions of the package manual are available in the <code class="file">doc</code> directory of the package.</p>
<p><a id="X851A50E6810EF8C5" name="X851A50E6810EF8C5"></a></p>
<h4>4.2 <span class="Heading">User Preferences of the <strong class="pkg">AtlasRep</strong> Package</span></h4>
<p>This section describes global parameters for which it might make sense to change their defaults, using <strong class="pkg">GAP</strong>'s user preferences (see <a href="../../../doc/ref/chap3.html#X7B0AD104839B6C3C"><span class="RefLink">Reference: Configuring User preferences</span></a>).</p>
<ul>
<li><p>Is access to remote data allowed (see Section <a href="chap4.html#X7C3293A98577EE68"><span class="RefLink">4.2-1</span></a>)? If yes then also the following parameters are of interest.</p>
<ul>
<li><p>From where can the data be fetched (see Section <a href="chap4.html#X7F21FFBE7F8108E4"><span class="RefLink">4.2-3</span></a>)?</p>
</li>
<li><p>Where are local copies of these data stored (see Section <a href="chap4.html#X7C36E9A78021A71A"><span class="RefLink">4.2-2</span></a>)?</p>
</li>
<li><p>Shall files be compressed after they have been downloaded (see Section <a href="chap4.html#X8766BE5D7AD6C526"><span class="RefLink">4.2-4</span></a>)?</p>
</li>
</ul>
</li>
<li><p>The following parameters influence reading and writing of local files.</p>
<ul>
<li><p>What shall actually happen when data are requested by the interface functions (see Section <a href="chap4.html#X81AD105979465162"><span class="RefLink">4.2-5</span></a>)?</p>
</li>
<li><p>If the value of the user preference <code class="code">FileAccessFunctions</code> contains <code class="code">"direct access to a local server"</code>, what is its path (see Section <a href="chap4.html#X85C48D6D81095161"><span class="RefLink">4.2-6</span></a>)?</p>
</li>
<li><p>Shall <code class="func">ScanMeatAxeFile</code> (<a href="chap7.html#X83D5103780E1238F"><span class="RefLink">7.3-1</span></a>) focus on small runtime or on small space when reading <strong class="pkg">MeatAxe</strong> text files (see Section <a href="chap4.html#X79993585808450FA"><span class="RefLink">4.2-7</span></a>)?</p>
</li>
<li><p>Which kind of headers shall <code class="func">MeatAxeString</code> (<a href="chap7.html#X7DDD09BE87063052"><span class="RefLink">7.3-2</span></a>) create (see Section <a href="chap4.html#X7B8F757B85F87936"><span class="RefLink">4.2-8</span></a>)?</p>
</li>
<li><p>Shall <code class="func">MeatAxeString</code> (<a href="chap7.html#X7DDD09BE87063052"><span class="RefLink">7.3-2</span></a>) interpret permutation matrices more as permutations (mode 2) or as matrices (mode 1 or 6) (see Section <a href="chap4.html#X7941C4378261E28A"><span class="RefLink">4.2-9</span></a>)?</p>
</li>
<li><p>Shall the default for <code class="func">CMtxBinaryFFMatOrPerm</code> (<a href="chap7.html#X8477AA668733255C"><span class="RefLink">7.3-4</span></a>) be to write binary files of zero-based or one-based permutations (see Section <a href="chap4.html#X877E40DB7A4E36C9"><span class="RefLink">4.2-10</span></a>)?</p>
</li>
</ul>
</li>
<li><p>Which function is used by <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>) for printing to the screen (see Section <a href="chap4.html#X81F055037F9D3068"><span class="RefLink">4.2-11</span></a>)?</p>
</li>
<li><p>How does <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>) mark data that do not belong to the core database (see Section <a href="chap4.html#X862C660878D422FA"><span class="RefLink">4.2-12</span></a>)?</p>
</li>
<li><p>Shall debug messages be printed when local data files are read (see Section <a href="chap4.html#X80958D068147325B"><span class="RefLink">4.2-13</span></a>)?</p>
</li>
</ul>
<p><a id="X7C3293A98577EE68" name="X7C3293A98577EE68"></a></p>
<h5>4.2-1 <span class="Heading">User preference <code class="code">AtlasRepAccessRemoteFiles</code></span></h5>
<p>The value <code class="keyw">true</code> (the default) allows the <strong class="pkg">AtlasRep</strong> package to fetch data files that are not yet locally available. If the value is <code class="keyw">false</code> then only those data files can be used that are available locally.</p>
<p>If you are working offline then you should set the value to <code class="keyw">false</code>.</p>
<p>Changing the value in a running <strong class="pkg">GAP</strong> session does not affect the information shown by <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>), this information depends on the value of the preference at the time when the <strong class="pkg">AtlasRep</strong> package and its data extensions get loaded.</p>
<p><a id="X7C36E9A78021A71A" name="X7C36E9A78021A71A"></a></p>
<h5>4.2-2 <span class="Heading">User preference <code class="code">AtlasRepDataDirectory</code></span></h5>
<p>The value must be a string that is either empty or the filename of a directory (in the sense of <code class="func">IsDirectoryPath</code> (<a href="../../../doc/ref/chap9.html#X7D1BE00F83C4EEE8"><span class="RefLink">Reference: IsDirectoryPath</span></a>)) that contains the directories in which downloaded data will be stored.</p>
<p>An empty string means that downloaded data are just kept in the <strong class="pkg">GAP</strong> session but not saved to local files.</p>
<p>The default depends on the user's permissions for the subdirectories <code class="file">dataext</code>, <code class="file">datagens</code>, <code class="file">dataword</code> of the <strong class="pkg">AtlasRep</strong> directory: If these directories are writable for the user then the installation path of the <strong class="pkg">AtlasRep</strong> package (including a trailing slash symbol) is taken. If this is not the case but the currentl <strong class="pkg">GAP</strong> session is running inside a <strong class="pkg">Julia</strong> session then a <strong class="pkg">Julia</strong> scratchspace is taken, otherwise the default is an empty string.</p>
<p><a id="X7F21FFBE7F8108E4" name="X7F21FFBE7F8108E4"></a></p>
<h5>4.2-3 <span class="Heading">User preference <code class="code">AtlasRepTOCData</code></span></h5>
<p>The value must be a list of strings of the form <code class="code">"ID|address"</code> where <code class="code">ID</code> is the id of a part of the database and <code class="code">address</code> is an URL or a file path (as an absolute path or relative to the user's home directory, cf. <code class="func">Directory</code> (<a href="../../../doc/ref/chap9.html#X86A71E927EEC7EAD"><span class="RefLink">Reference: Directory</span></a>)) of a readable JSON format file that contain the table of contents of this part, see <code class="func">StringOfAtlasTableOfContents</code> (<a href="chap5.html#X81C5440983E47DBD"><span class="RefLink">5.1-3</span></a>).</p>
<p>The default lists four entries: the core database, the data distributed with the <strong class="pkg">AtlasRep</strong> package, and the data that belong to the packages <strong class="pkg">MFER</strong> and <strong class="pkg">CTBlocks</strong>.</p>
<p><a id="X8766BE5D7AD6C526" name="X8766BE5D7AD6C526"></a></p>
<h5>4.2-4 <span class="Heading">User preference <code class="code">CompressDownloadedMeatAxeFiles</code></span></h5>
<p>When used with UNIX, <strong class="pkg">GAP</strong> can read <code class="file">gzip</code>ped files, see <a href="../../../doc/ref/chap3.html#X7CB282757ACB1C09"><span class="RefLink">Reference: Saving and Loading a Workspace</span></a>. If the package's user preference <code class="code">CompressDownloadedMeatAxeFiles</code> has the value <code class="keyw">true</code> then each <strong class="pkg">MeatAxe</strong> format text file that is downloaded from the internet is afterwards compressed with <code class="file">gzip</code>. The default value is <code class="keyw">false</code>.</p>
<p>Compressing files saves a lot of space if many <strong class="pkg">MeatAxe</strong> format files are accessed. (Note that data files in other formats are very small.) For example, at the time of the release of version 2.0 the core database contained about <span class="SimpleMath">8400</span> data files in <strong class="pkg">MeatAxe</strong> format, which needed about <span class="SimpleMath">1400</span> MB in uncompressed text format and about <span class="SimpleMath">275</span> MB in compressed text format.</p>
<p><a id="X81AD105979465162" name="X81AD105979465162"></a></p>
<h5>4.2-5 <span class="Heading">User preference <code class="code">FileAccessFunctions</code></span></h5>
<p>This preference allows one to customize what actually happens when data are requested by the interface functions: Is it necessary to download some files? If yes then which files are downloaded? If no then which files are actually read into <strong class="pkg">GAP</strong>?</p>
<p>Currently one can choose among the following features.</p>
<ol>
<li><p>Download/read <strong class="pkg">MeatAxe</strong> text files.</p>
</li>
<li><p>Prefer downloading/reading <strong class="pkg">MeatAxe</strong> binary files.</p>
</li>
<li><p>Prefer reading locally available data files.</p>
</li>
</ol>
<p>(Of course files can be downloaded only if the user preference <code class="code">AtlasRepAccessRemoteFiles</code> has the value <code class="keyw">true</code>, see Section <a href="chap4.html#X7C3293A98577EE68"><span class="RefLink">4.2-1</span></a>.)</p>
<p>This feature could be used more generally, see Section <a href="chap7.html#X81C5B5E78215169D"><span class="RefLink">7.2</span></a> for technical details and the possibility to add other features.</p>
<p><a id="X85C48D6D81095161" name="X85C48D6D81095161"></a></p>
<h5>4.2-6 <span class="Heading">User preference <code class="code">AtlasRepLocalServerPath</code></span></h5>
<p>If the data of the core database are available locally (for example because one has access to a local mirror of the data) then one may prefer reading these files instead of downloading data. In order to achieve this, one can set the user preference <code class="code">AtlasRepLocalServerPath</code> and add <code class="code">"direct access to a local server"</code> to the user preference <code class="code">FileAccessFunctions</code>, see Section <a href="chap4.html#X81AD105979465162"><span class="RefLink">4.2-5</span></a>.</p>
<p>The value must be a string that is the filename of a directory (in the sense of <code class="func">IsDirectoryPath</code> (<a href="../../../doc/ref/chap9.html#X7D1BE00F83C4EEE8"><span class="RefLink">Reference: IsDirectoryPath</span></a>)) that contains the data of the <strong class="pkg">ATLAS</strong> of Group Representations, in the same directory tree structure as on the <strong class="pkg">ATLAS</strong> server.</p>
<p><a id="X79993585808450FA" name="X79993585808450FA"></a></p>
<h5>4.2-7 <span class="Heading">User preference <code class="code">HowToReadMeatAxeTextFiles</code></span></h5>
<p>The value <code class="code">"fast"</code> means that <code class="func">ScanMeatAxeFile</code> (<a href="chap7.html#X83D5103780E1238F"><span class="RefLink">7.3-1</span></a>) reads text files via <code class="func">StringFile</code> (<a href="../../../pkg/gapdoc/doc/chap6.html#X7E14D32181FBC3C3"><span class="RefLink">GAPDoc: StringFile</span></a>). Otherwise each file containing a matrix over a finite field is read line by line via <code class="func">ReadLine</code> (<a href="../../../doc/ref/chap10.html#X7D2CA44C7D110C4F"><span class="RefLink">Reference: ReadLine</span></a>), and the <strong class="pkg">GAP</strong> matrix is constructed line by line, in a compressed representation (see <a href="../../../doc/ref/chap23.html#X8679F7DD7DFCBD9C"><span class="RefLink">Reference: Row Vectors over Finite Fields</span></a> and <a href="../../../doc/ref/chap24.html#X873822B6830CE367"><span class="RefLink">Reference: Matrices over Finite Fields</span></a>); this makes it possible to read large matrices in a reasonable amount of space.</p>
<p>The <code class="func">StringFile</code> (<a href="../../../pkg/gapdoc/doc/chap6.html#X7E14D32181FBC3C3"><span class="RefLink">GAPDoc: StringFile</span></a>) approach is faster but needs more intermediate space when text files containing matrices over finite fields are read. For example, a <span class="SimpleMath">4370</span> by <span class="SimpleMath">4370</span> matrix over the field with two elements (as occurs for an irreducible representation of the Baby Monster) requires less than <span class="SimpleMath">3</span> MB space in <strong class="pkg">GAP</strong> but the corresponding <strong class="pkg">MeatAxe</strong> format text file is more than <span class="SimpleMath">19</span> MB large. This means that when one reads the file with the fast variant, <strong class="pkg">GAP</strong> will temporarily grow by more than this value.</p>
<p>Note that this parameter has an effect only when <code class="func">ScanMeatAxeFile</code> (<a href="chap7.html#X83D5103780E1238F"><span class="RefLink">7.3-1</span></a>) is used. It has no effect for example if <strong class="pkg">MeatAxe</strong> binary files are read, cf. <code class="func">FFMatOrPermCMtxBinary</code> (<a href="chap7.html#X872FA00C7F791FBB"><span class="RefLink">7.3-5</span></a>).</p>
<p><a id="X7B8F757B85F87936" name="X7B8F757B85F87936"></a></p>
<h5>4.2-8 <span class="Heading">User preference <code class="code">WriteHeaderFormatOfMeatAxeFiles</code></span></h5>
<p>This user preference determines the format of the header lines of <strong class="pkg">MeatAxe</strong> format strings created by <code class="func">MeatAxeString</code> (<a href="chap7.html#X7DDD09BE87063052"><span class="RefLink">7.3-2</span></a>), see the <code class="code">C</code>-<strong class="pkg">MeatAxe</strong> manual <a href="chapBib.html#biBCMeatAxe">[Rin]</a> for details. The following values are supported.</p>
<dl>
<dt><strong class="Mark"><code class="code">"numeric"</code></strong></dt>
<dd><p>means that the header line of the returned string consists of four integers (in the case of a matrix these are mode, row number, column number and field size),</p>
</dd>
<dt><strong class="Mark"><code class="code">"numeric (fixed)"</code></strong></dt>
<dd><p>means that the header line of the returned string consists of four integers as in the case <code class="code">"numeric"</code>, but additionally each integer is right aligned in a substring of length (at least) six,</p>
</dd>
<dt><strong class="Mark"><code class="code">"textual"</code></strong></dt>
<dd><p>means that the header line of the returned string consists of assignments such as <code class="code">matrix field=2</code>.</p>
</dd>
</dl>
<p><a id="X7941C4378261E28A" name="X7941C4378261E28A"></a></p>
<h5>4.2-9 <span class="Heading">User preference <code class="code">WriteMeatAxeFilesOfMode2</code></span></h5>
<p>The value <code class="keyw">true</code> means that the function <code class="func">MeatAxeString</code> (<a href="chap7.html#X7DDD09BE87063052"><span class="RefLink">7.3-2</span></a>) will encode permutation matrices via mode 2 descriptions, that is, the first entry in the header line is 2, and the following lines contain the positions of the nonzero entries. If the value is <code class="keyw">false</code> (the default) then <code class="func">MeatAxeString</code> (<a href="chap7.html#X7DDD09BE87063052"><span class="RefLink">7.3-2</span></a>) encodes permutation matrices via mode 1 or mode 6 descriptions, that is, the lines contain the matrix entries.</p>
<p><a id="X877E40DB7A4E36C9" name="X877E40DB7A4E36C9"></a></p>
<h5>4.2-10 <span class="Heading">User preference <code class="code">BaseOfMeatAxePermutation</code></span></h5>
<p>The value <span class="SimpleMath">0</span> means that the function <code class="func">CMtxBinaryFFMatOrPerm</code> (<a href="chap7.html#X8477AA668733255C"><span class="RefLink">7.3-4</span></a>) writes zero-based permutations, that is, permutations acting on the points from <span class="SimpleMath">0</span> to the degree minus one; this is achieved by shifting down all images of the <strong class="pkg">GAP</strong> permutation by one. The value <span class="SimpleMath">1</span> (the default) means that the permutation stored in the binary file acts on the points from <span class="SimpleMath">1</span> to the degree.</p>
<p>Up to version 2.3 of the <code class="code">C</code>-<strong class="pkg">MeatAxe</strong>, permutations in binary files were always one-based. Zero-based permutations were introduced in version 2.4.</p>
<p><a id="X81F055037F9D3068" name="X81F055037F9D3068"></a></p>
<h5>4.2-11 <span class="Heading">User preference <code class="code">DisplayFunction</code></span></h5>
<p>The way how <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>) shows the requested overview is controlled by the package <strong class="pkg">AtlasRep</strong>'s user preference <code class="code">DisplayFunction</code>. The value must be a string that evaluates to a <strong class="pkg">GAP</strong> function. The default value is <code class="code">"Print"</code> (see <code class="func">Print</code> (<a href="../../../doc/ref/chap6.html#X7AFA64D97A1F39A3"><span class="RefLink">Reference: Print</span></a>)), other useful values are <code class="code">"PrintFormattedString"</code> (see <code class="func">PrintFormattedString</code> (<a href="../../../pkg/gapdoc/doc/chap6.html#X812A8326844BC910"><span class="RefLink">GAPDoc: PrintFormattedString</span></a>)) and <code class="code">"AGR.Pager"</code>; the latter means that <code class="func">Pager</code> (<a href="../../../doc/ref/chap2.html#X7ED03E41792C3840"><span class="RefLink">Reference: Pager</span></a>) is called with the <code class="code">formatted</code> option, which is necessary for switching off <strong class="pkg">GAP</strong>'s automatic line breaking.</p>
<p><a id="X862C660878D422FA" name="X862C660878D422FA"></a></p>
<h5>4.2-12 <span class="Heading">User preference <code class="code">AtlasRepMarkNonCoreData</code></span></h5>
<p>The value is a string (the default is a star '*') that is used in <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>) to mark data that do not belong to the core database, see Section <a href="chap5.html#X7A6024EC87A95E0B"><span class="RefLink">5.2</span></a>.</p>
<p><a id="X80958D068147325B" name="X80958D068147325B"></a></p>
<h5>4.2-13 <span class="Heading">User preference <code class="code">DebugFileLoading</code></span></h5>
<p>If the value is <code class="keyw">true</code> then debug messages are printed before and after data files get loaded. The default value is <code class="keyw">false</code>.</p>
<p><a id="X850D135E79EFF3F7" name="X850D135E79EFF3F7"></a></p>
<h5>4.2-14 <span class="Heading">User preference <code class="code">AtlasRepJsonFilesAddresses</code></span></h5>
<p>The value, if set, must be a list of length two, the first entry being an URL describing a directory that contains Json format files of the available matrix representations in characteristic zero, and the second being a directory path where these files shall be stored locally. If the value is set (this is the default) then the functions of the package use the Json format files instead of the GAP format files.</p>
<p><a id="X7C50F18587ADC3B5" name="X7C50F18587ADC3B5"></a></p>
<h4>4.3 <span class="Heading">Web Contents for the <strong class="pkg">AtlasRep</strong> Package</span></h4>
<p>The <span class="URL"><a href="https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep">home page of the <strong class="pkg">AtlasRep</strong> package</a></span> provides</p>
<ul>
<li><p>package archives,</p>
</li>
<li><p>introductory package information,</p>
</li>
<li><p>the current <em>table of contents</em> of core data in the file <span class="URL"><a href="https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/atlasprm.json"><code class="file">atlasprm.json</code></a></span> of the package, cf. <code class="func">StringOfAtlasTableOfContents</code> (<a href="chap5.html#X81C5440983E47DBD"><span class="RefLink">5.1-3</span></a>),</p>
</li>
<li><p>the <span class="URL"><a href="https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/htm/data/changes.htm">list of changes of remote core data files</a></span>,</p>
</li>
<li><p>a <span class="URL"><a href="https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/atlasrepdata.tar.gz">starter archive</a></span> containing many small representations and programs, and</p>
</li>
<li><p>an <span class="URL"><a href="https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/htm/data">overview of the core data</a></span> in a similar format as the information shown by the function <code class="func">DisplayAtlasInfo</code> (<a href="chap3.html#X79DACFFA7E2D1A99"><span class="RefLink">3.5-1</span></a>) of the package; more details can be found on the <span class="URL"><a href="http://atlas.math.rwth-aachen.de/Atlas/v3">home page of the <strong class="pkg">ATLAS</strong> of Group Representations</a></span>.</p>
</li>
</ul>
<p><a id="X7FB64AD37D4620E6" name="X7FB64AD37D4620E6"></a></p>
<h4>4.4 <span class="Heading">Extending the <strong class="pkg">ATLAS</strong> Database</span></h4>
<p>Users who have computed new representations that might be interesting for inclusion into the <strong class="pkg">ATLAS</strong> of Group representations can send the data in question to <span class="URL"><a href="mailto:R.A.Wilson@qmul.ac.uk">R.A.Wilson@qmul.ac.uk</a></span>.</p>
<p>It is also possible to make additional representations and programs accessible for the <strong class="pkg">GAP</strong> interface, and to use these <q>private</q> data in the same way as the core data. See Chapter <a href="chap5.html#X7B0718A178BB10CA"><span class="RefLink">5</span></a> for details.</p>
<div class="chlinkprevnextbot"> <a href="chap0.html">[Top of Book]</a> <a href="chap0.html#contents">[Contents]</a> <a href="chap3.html">[Previous Chapter]</a> <a href="chap5.html">[Next Chapter]</a> </div>
<div class="chlinkbot"><span class="chlink1">Goto Chapter: </span><a href="chap0.html">Top</a> <a href="chap1.html">1</a> <a href="chap2.html">2</a> <a href="chap3.html">3</a> <a href="chap4.html">4</a> <a href="chap5.html">5</a> <a href="chap6.html">6</a> <a href="chap7.html">7</a> <a href="chapBib.html">Bib</a> <a href="chapInd.html">Ind</a> </div>
<hr />
<p class="foot">generated by <a href="https://www.math.rwth-aachen.de/~Frank.Luebeck/GAPDoc">GAPDoc2HTML</a></p>
</body>
</html>
|
