Sophie: gap-system-packages-4.4.12-5mdv2010.0 i586

gap-system-packages-4.4.12-5mdv2010.0.i586.rpm

<html><head><title>[cryst] 1 Introduction</title></head>
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<h1>1 Introduction</h1><p>
<p>
<a name = "I0"></a>

The <font face="Gill Sans,Helvetica,Arial">Cryst</font> package, previously known as <font face="Gill Sans,Helvetica,Arial">CrystGAP</font>, provides 
functions for the computation with affine crystallographic groups, 
in particular space groups. For the definition of the standard 
crystallographic notions we refer to the International Tables 
<a href="biblio.htm#Hah95"><cite>Hah95</cite></a>, in particular the chapter by Wondratschek <a href="biblio.htm#Won95"><cite>Won95</cite></a>,
and to the introductory chapter in <a href="biblio.htm#BBNWZ78"><cite>BBNWZ78</cite></a>. The principal 
algorithms used in this package are described in <a href="biblio.htm#EGN97"><cite>EGN97</cite></a>.
<p>
The present version for <font face="Gill Sans,Helvetica,Arial">GAP</font>&nbsp;4 has been considerably reworked from
an earlier version for <font face="Gill Sans,Helvetica,Arial">GAP</font>&nbsp;3.4.4. Most of the porting to <font face="Gill Sans,Helvetica,Arial">GAP</font>&nbsp;4
has been done by Franz G&auml;hler. Besides affine crystallographic
groups acting from the right, also affine crystallographic groups acting 
from the left are now fully supported. Many algorithms have been added, 
extended, or improved in other ways.
<p>
Our warmest thanks go the Max Neunh&ouml;ffer, whose extensive
testing of the <font face="Gill Sans,Helvetica,Arial">GAP</font> 4 version of <font face="Gill Sans,Helvetica,Arial">Cryst</font> in connection with <font face="Gill Sans,Helvetica,Arial">XGAP</font> 
uncovered several bugs and led to many performance improvements.
<p>
<font face="Gill Sans,Helvetica,Arial">Cryst</font> is implemented in the <font face="Gill Sans,Helvetica,Arial">GAP</font>&nbsp;4 language, and runs on any 
system supporting <font face="Gill Sans,Helvetica,Arial">GAP</font>&nbsp;4. However, certain commands may require 
that other GAP packages such as <font face="Gill Sans,Helvetica,Arial">CARAT</font> or <font face="Gill Sans,Helvetica,Arial">XGAP</font> are installed.
In particular, the routines in Section&nbsp;<a href="CHAP002.htm#SECT008">Normalizers</a> are likely
to require <font face="Gill Sans,Helvetica,Arial">CARAT</font>, and the function WyckoffGraph (see&nbsp;<a href="CHAP002.htm#SSEC007.9">WyckoffGraph</a>)
requires <font face="Gill Sans,Helvetica,Arial">XGAP</font>. Both <font face="Gill Sans,Helvetica,Arial">CARAT</font> and <font face="Gill Sans,Helvetica,Arial">XGAP</font> are available only under Unix.
<p>
The <font face="Gill Sans,Helvetica,Arial">Cryst</font> package is loaded with the command
<pre>
gap&gt; RequirePackage( "cryst" ); 
true
</pre>
<p>
<font face="Gill Sans,Helvetica,Arial">Cryst</font> has been developed by
<p>
<dl compact>
<dt>Bettina Eick <dd>
Fachbereich Mathematik und Informatik <br>
Technische Universit&auml;t Braunschweig <br>
Pockelsstr. 14, D-38106 Braunschweig, Germany <br>
e-mail: <a href="mailto:b.eick@tu-bs.de">b.eick@tu-bs.de</a>
<p>
<dt>Franz G&auml;hler <dd>
Institut f&uuml;r Theoretische und Angewandte Physik, <br>
Universit&auml;t Stuttgart,
D-70550 Stuttgart, Germany  <br>
e-mail: <a href="mailto:gaehler@itap.physik.uni-stuttgart.de">gaehler@itap.physik.uni-stuttgart.de</a>
<p>
<dt>Werner Nickel <dd>
Fachbereich Mathematik, AG2,
Technische Universit&auml;t Darmstadt,  <br>
Schlossgartenstra&szlig;e 7, D-64289 Darmstadt, Germany  <br>
e-mail: <a href="mailto:nickel@mathematik.tu-darmstadt.de">nickel@mathematik.tu-darmstadt.de</a>
</dl>
<p>
Please send bug reports, suggestions and other comments to any of these
e-mail addresses.
<p>
<p>
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<P>
<address>cryst manual<br>November 2008
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