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| 3 | <meta http-equiv="CONTENT-TYPE" content="text/html; charset=windows-1252"><title>PALM |
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| 4 | 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 | </style></head> |
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| 9 | |
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| 10 | <body style="direction: ltr;" lang="en-US"><h4 style="line-height: 100%;"><font size="4">4.5.6 |
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| 11 | Plots of compressed |
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| 12 | 3d volume data with AVS</font></h4> |
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| 13 | <p style="line-height: 100%;">Files containing 3d volume |
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| 14 | data usually |
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| 15 | need large amounts of disc space. For parallel runs, the disc space |
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| 16 | requirement can |
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| 17 | be clearly reduced if the data are output in compressed format (note: |
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| 18 | currently a data |
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| 19 | compression is permitted only for parallel runs on Cray-T3E). Data |
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| 20 | compression |
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| 21 | can switched on by setting the initialization parameter <a href="chapter_4.2.html#do3d_compress">do3d_compress</a> |
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| 22 | = <i>.TRUE.</i> and by assigning the desired accuracy |
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| 23 | (number of |
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| 24 | significant digits) via <a href="chapter_4.2.html#do3d_precision">do3d_precision</a>. |
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| 25 | A separate accuracy must be assigned for each individual quantity. |
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| 26 | Using uncompressed data, each grid point value is |
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| 27 | represented by a 32-bit real number, in case of compression the grid |
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| 28 | point values are represented by integers whose length depends |
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| 29 | on the desired accuracy (in general clearly smaller than 32 bits). |
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| 30 | The individual grid point values are packed into 32-bit integers and |
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| 31 | output. To plot these compressed data the following output command must |
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| 32 | be inserted into the |
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| 33 | <span style="font-weight: bold;">mrun</span> |
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| 34 | configuration file<b> </b>(in |
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| 35 | addition to the steps described |
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| 36 | in <a href="chapter_4.5.5.html">chapter |
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| 37 | 4.5.5</a>): </p> |
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| 38 | <ul> <pre style="margin-bottom: 0.5cm; line-height: 100%;"><font style="font-size: 10pt;" size="2">OC:[[ -f PLOT3D_COMPRESSED ]] && tar cf PLOT3D_DATA PLOT3D_DATA_*</font></pre></ul> |
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| 39 | <p style="line-height: 100%;">If a file named <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt> |
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| 40 | exists in the local working directory, <tt><font face="Thorndale, serif">t</font></tt><font face="Thorndale, serif">he |
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| 41 | files produ</font>ced by the individual processors are packed |
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| 42 | into one |
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| 43 | file (<tt><font style="font-size: 10pt;" size="2">PLOT3D_DATA</font></tt>) |
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| 44 | using the "tar" |
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| 45 | command. The flag file |
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| 46 | <tt><font size="2">PLOT3D_COMPRESSED </font></tt>is |
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| 47 | created by PALM |
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| 48 | whenever data in compressed form is to be output. For |
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| 49 | uncompressed output, the individual files have to be joined via the |
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| 50 | program <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font> |
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| 51 | </tt>. In this case, an additional output command is also |
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| 52 | necessary |
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| 53 | (see chapter 4.5.5). For compressed output, this output command may |
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| 54 | remain |
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| 55 | unchanged in the configuration file, since <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font></tt> |
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| 56 | recognizes the |
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| 57 | ex<font face="Thorndale, serif">isten</font>ce of <tt><font style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt> |
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| 58 | and carries out no actions in such cases. </p> |
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| 59 | <p style="line-height: 100%;">The file connection |
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| 60 | statements for the |
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| 61 | local file <a href="chapter_3.4.html#PLOT3D_DATA">PLOT3D_DATA</a> |
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| 62 | and all further necessary statements to create plots of 3d volume |
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| 63 | data can be found in <a href="chapter_4.5.5.html">chapter |
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| 64 | 4.5.5</a>. </p> |
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| 65 | <p style="line-height: 100%;">After been transferred to |
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| 66 | the local |
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| 67 | computer |
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| 68 | of the user, the tar file with the compressed data cannot be read |
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| 69 | with the usual <span style="font-weight: bold;">AVS</span> |
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| 70 | module |
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| 71 | “read field”. Alternatively, |
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| 72 | the module “read_compressed_field” particularly |
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| 73 | developed |
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| 74 | for this purpose must be used. This module is located in a module |
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| 75 | library under: </p> |
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| 76 | <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 |
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| 77 | AVS |
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| 78 | (network editor - > module |
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| 79 | tools - > read module library) and then it can be used like all |
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| 80 | other modules. <a href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/read_compressed_field.html">Further |
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| 81 | information</a> about using this module is available (e.g. for |
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| 82 | accelerated treatment of compressed data with <span style="font-weight: bold;">AVS</span> the module |
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| 83 | <a href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/write_compressed_field.html">write_compressed_field</a> |
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| 84 | is available). <br> |
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| 85 | <br> |
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| 86 | </p> |
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| 87 | <hr><p style="line-height: 100%;"><br> |
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| 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%;"> <i>Last |
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| 89 | change: </i> $Id: chapter_4.5.6.html 62 2007-03-13 02:52:40Z steinfeld $</p> |
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| 90 | </body></html> |
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