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[197]3<meta http-equiv="CONTENT-TYPE" content="text/html; charset=windows-1252"><title>PALM chapter 4.5.6</title> <meta name="GENERATOR" content="StarOffice 7 (Win32)"> <meta name="AUTHOR" content="Siegfried Raasch"> <meta name="CREATED" content="20041029;13171001"> <meta name="CHANGED" content="20041117;12013945"> <meta name="KEYWORDS" content="parallel LES model"> <style>
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8<body style="direction: ltr;" lang="en-US"><h4 style="line-height: 100%;"><font size="4">4.5.6
9Plots of compressed
[5]103d volume data with AVS</font></h4>
[62]11<p style="line-height: 100%;">Files containing 3d volume
12data usually
[5]13need large amounts of disc space. For parallel runs, the disc space
14requirement can
15be clearly reduced if the data are output in compressed format (note:
16currently a data
17compression is permitted only for parallel runs on Cray-T3E). Data
18compression
[62]19can switched on by setting the initialization parameter <a href="chapter_4.2.html#do3d_compress">do3d_compress</a>
20= <i>.TRUE.</i> and by assigning the desired accuracy
21(number of
[197]22significant digits) via <a href="chapter_4.2.html#do3d_comp_prec">do3d_comp_prec</a>.
[5]23A separate accuracy must be assigned for each individual quantity.
24Using uncompressed data, each grid point value is
25represented by a 32-bit real number, in case of compression the grid
26point values are represented by integers whose length depends
27on the desired accuracy (in general clearly smaller than 32 bits).
28The individual grid point values are packed into 32-bit integers and
29output. To plot these compressed data the following output command must
30be inserted into the
[62]31<span style="font-weight: bold;">mrun</span>
32configuration file<b> </b>(in
[5]33addition to the steps described
34in <a href="chapter_4.5.5.html">chapter
354.5.5</a>): </p>
[62]36<ul> <pre style="margin-bottom: 0.5cm; line-height: 100%;"><font style="font-size: 10pt;" size="2">OC:[[ -f PLOT3D_COMPRESSED ]] &amp;&amp; tar cf PLOT3D_DATA PLOT3D_DATA_*</font></pre></ul>
37<p style="line-height: 100%;">If a file named <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt>
38exists in the local working directory, <tt><font face="Thorndale, serif">t</font></tt><font face="Thorndale, serif">he
39files produ</font>ced by the individual processors are packed
40into one
[5]41file (<tt><font style="font-size: 10pt;" size="2">PLOT3D_DATA</font></tt>)
42using the "tar"
43command. The flag file
[62]44<tt><font size="2">PLOT3D_COMPRESSED </font></tt>is
45created by PALM
[5]46whenever data in compressed form is to be output. For
47uncompressed output, the individual files have to be joined via the
48program <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font>
[62]49</tt>. In this case, an additional output command is also
50necessary
[5]51(see chapter 4.5.5). For compressed output, this output command may
52remain
[62]53unchanged in the configuration file, since <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font></tt>
[5]54recognizes the
[62]55ex<font face="Thorndale, serif">isten</font>ce of <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt>
[5]56and carries out no actions in such cases. </p>
[62]57<p style="line-height: 100%;">The file connection
58statements for the
[5]59local file <a href="chapter_3.4.html#PLOT3D_DATA">PLOT3D_DATA</a>
60and all further necessary statements to create plots of 3d volume
61data can be found in <a href="chapter_4.5.5.html">chapter
624.5.5</a>. </p>
[62]63<p style="line-height: 100%;">After been transferred to
64the local
[5]65computer
66of the user, the tar file with the compressed data cannot be read
[62]67with the usual <span style="font-weight: bold;">AVS</span>
68module
69&ldquo;read field&rdquo;. Alternatively,
70the module &ldquo;read_compressed_field&rdquo; particularly
71developed
[5]72for this purpose must be used. This module is located in a module
73library under: </p>
[62]74<pre style="margin-bottom: 0.5cm; line-height: 100%;"><font style="font-size: 10pt;" size="2">http://www.muk.uni-hannover.de/~raasch/PALM_group/AVS/Libraries/palm</font></pre><p style="line-height: 100%;">This module must be loaded within
75AVS
[5]76(network editor - &gt; module
77tools - &gt; read module library) and then it can be used like all
[62]78other modules. <a href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/read_compressed_field.html">Further
[5]79information</a> about using this module is available (e.g. for
[62]80accelerated treatment of compressed data with <span style="font-weight: bold;">AVS</span> the module
81<a href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/write_compressed_field.html">write_compressed_field</a>
[5]82is available). <br>
83&nbsp; <br>
84&nbsp; </p>
[62]85<hr><p style="line-height: 100%;"><br>
86<font color="#000080"><font color="#000080"><a href="chapter_4.5.5.html"><font color="#000080"><img src="left.gif" name="Grafik1" align="bottom" border="2" height="32" width="32"></font></a><a href="index.html"><font color="#000080"><img src="up.gif" name="Grafik2" align="bottom" border="2" height="32" width="32"></font></a><a href="chapter_4.5.7.html"><font color="#000080"><img src="right.gif" name="Grafik3" align="bottom" border="2" height="32" width="32"></font></a></font></font></p><p style="line-height: 100%;">&nbsp;<i>Last
87change:&nbsp;</i> $Id: chapter_4.5.6.html 197 2008-09-16 15:29:03Z raasch $</p>
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