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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
3<meta http-equiv="CONTENT-TYPE" content="text/html; charset=windows-1252"><title>PALM
4chapter 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>
6@page { size: 21cm 29.7cm }
10<body style="direction: ltr;" lang="en-US"><h4 style="line-height: 100%;"><font size="4">4.5.6
11Plots of compressed
123d volume data with AVS</font></h4>
13<p style="line-height: 100%;">Files containing 3d volume
14data usually
15need large amounts of disc space. For parallel runs, the disc space
16requirement can
17be clearly reduced if the data are output in compressed format (note:
18currently a data
19compression is permitted only for parallel runs on Cray-T3E). Data
21can switched on by setting the initialization parameter <a href="chapter_4.2.html#do3d_compress">do3d_compress</a>
22= <i>.TRUE.</i> and by assigning the desired accuracy
23(number of
24significant digits) via <a href="chapter_4.2.html#do3d_precision">do3d_precision</a>.
25A separate accuracy must be assigned for each individual quantity.
26Using uncompressed data, each grid point value is
27represented by a 32-bit real number, in case of compression the grid
28point values are represented by integers whose length depends
29on the desired accuracy (in general clearly smaller than 32 bits).
30The individual grid point values are packed into 32-bit integers and
31output. To plot these compressed data the following output command must
32be inserted into the
33<span style="font-weight: bold;">mrun</span>
34configuration file<b> </b>(in
35addition to the steps described
36in <a href="chapter_4.5.5.html">chapter
374.5.5</a>): </p>
38<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>
39<p style="line-height: 100%;">If a file named <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt>
40exists in the local working directory, <tt><font face="Thorndale, serif">t</font></tt><font face="Thorndale, serif">he
41files produ</font>ced by the individual processors are packed
42into one
43file (<tt><font style="font-size: 10pt;" size="2">PLOT3D_DATA</font></tt>)
44using the "tar"
45command. The flag file
46<tt><font size="2">PLOT3D_COMPRESSED </font></tt>is
47created by PALM
48whenever data in compressed form is to be output. For
49uncompressed output, the individual files have to be joined via the
50program <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font>
51</tt>. In this case, an additional output command is also
53(see chapter 4.5.5). For compressed output, this output command may
55unchanged in the configuration file, since <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font></tt>
56recognizes the
57ex<font face="Thorndale, serif">isten</font>ce of <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt>
58and carries out no actions in such cases. </p>
59<p style="line-height: 100%;">The file connection
60statements for the
61local file <a href="chapter_3.4.html#PLOT3D_DATA">PLOT3D_DATA</a>
62and all further necessary statements to create plots of 3d volume
63data can be found in <a href="chapter_4.5.5.html">chapter
644.5.5</a>. </p>
65<p style="line-height: 100%;">After been transferred to
66the local
68of the user, the tar file with the compressed data cannot be read
69with the usual <span style="font-weight: bold;">AVS</span>
71&ldquo;read field&rdquo;. Alternatively,
72the module &ldquo;read_compressed_field&rdquo; particularly
74for this purpose must be used. This module is located in a module
75library under: </p>
76<pre style="margin-bottom: 0.5cm; line-height: 100%;"><font style="font-size: 10pt;" size="2"></font></pre><p style="line-height: 100%;">This module must be loaded within
78(network editor - &gt; module
79tools - &gt; read module library) and then it can be used like all
80other modules. <a href="">Further
81information</a> about using this module is available (e.g. for
82accelerated treatment of compressed data with <span style="font-weight: bold;">AVS</span> the module
83<a href="">write_compressed_field</a>
84is available). <br>
85&nbsp; <br>
86&nbsp; </p>
87<hr><p style="line-height: 100%;"><br>
88<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
89change:&nbsp;</i> $Id: chapter_4.5.6.html 62 2007-03-13 02:52:40Z raasch $</p>
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