| [5] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> |
|---|
| 2 | <html> |
|---|
| 3 | <head> |
|---|
| 4 | <meta http-equiv="CONTENT-TYPE" |
|---|
| 5 | content="text/html; charset=windows-1252"> |
|---|
| 6 | <title>PALM chapter 4.5.6</title> |
|---|
| 7 | <meta name="GENERATOR" content="StarOffice 7 (Win32)"> |
|---|
| 8 | <meta name="AUTHOR" content="Siegfried Raasch"> |
|---|
| 9 | <meta name="CREATED" content="20041029;13171001"> |
|---|
| 10 | <meta name="CHANGED" content="20041117;12013945"> |
|---|
| 11 | <meta name="KEYWORDS" content="parallel LES model"> |
|---|
| 12 | <style> |
|---|
| 13 | <!-- |
|---|
| 14 | @page { size: 21cm 29.7cm } |
|---|
| 15 | --> |
|---|
| 16 | </style> |
|---|
| 17 | </head> |
|---|
| 18 | <body dir="ltr" lang="en-US"> |
|---|
| 19 | <h4 style="line-height: 100%;"><font size="4">4.5.6 Plots of compressed |
|---|
| 20 | 3d volume data with AVS</font></h4> |
|---|
| 21 | <p style="line-height: 100%;">Files containing 3d volume data usually |
|---|
| 22 | need large amounts of disc space. For parallel runs, the disc space |
|---|
| 23 | requirement can |
|---|
| 24 | be clearly reduced if the data are output in compressed format (note: |
|---|
| 25 | currently a data |
|---|
| 26 | compression is permitted only for parallel runs on Cray-T3E). Data |
|---|
| 27 | compression |
|---|
| 28 | can switched on by setting the initialization parameter <a |
|---|
| 29 | href="chapter_4.2.html#do3d_compress">do3d_compress</a> |
|---|
| 30 | = <i>.TRUE.</i> and by assigning the desired accuracy (number of |
|---|
| 31 | significant digits) via <a href="chapter_4.2.html#do3d_precision">do3d_precision</a>. |
|---|
| 32 | A separate accuracy must be assigned for each individual quantity. |
|---|
| 33 | Using uncompressed data, each grid point value is |
|---|
| 34 | represented by a 32-bit real number, in case of compression the grid |
|---|
| 35 | point values are represented by integers whose length depends |
|---|
| 36 | on the desired accuracy (in general clearly smaller than 32 bits). |
|---|
| 37 | The individual grid point values are packed into 32-bit integers and |
|---|
| 38 | output. To plot these compressed data the following output command must |
|---|
| 39 | be inserted into the |
|---|
| 40 | <span style="font-weight: bold;">mrun</span> configuration file<b> </b>(in |
|---|
| 41 | addition to the steps described |
|---|
| 42 | in <a href="chapter_4.5.5.html">chapter |
|---|
| 43 | 4.5.5</a>): </p> |
|---|
| 44 | <ul> |
|---|
| 45 | <pre style="margin-bottom: 0.5cm; line-height: 100%;"><font |
|---|
| 46 | style="font-size: 10pt;" size="2">OC:[[ -f PLOT3D_COMPRESSED ]] && tar cf PLOT3D_DATA PLOT3D_DATA_*</font></pre> |
|---|
| 47 | </ul> |
|---|
| 48 | <p style="line-height: 100%;">If a file named <tt><font |
|---|
| 49 | style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt> |
|---|
| 50 | exists in the local working directory, <tt><font |
|---|
| 51 | face="Thorndale, serif">t</font></tt><font face="Thorndale, serif">he |
|---|
| 52 | files produ</font>ced by the individual processors are packed into one |
|---|
| 53 | file (<tt><font style="font-size: 10pt;" size="2">PLOT3D_DATA</font></tt>) |
|---|
| 54 | using the "tar" |
|---|
| 55 | command. The flag file |
|---|
| 56 | <tt><font size="2">PLOT3D_COMPRESSED </font></tt>is created by PALM |
|---|
| 57 | whenever data in compressed form is to be output. For |
|---|
| 58 | uncompressed output, the individual files have to be joined via the |
|---|
| 59 | program <tt><font style="font-size: 10pt;" size="2">combine_plot_fields.x</font> |
|---|
| 60 | </tt>. In this case, an additional output command is also necessary |
|---|
| 61 | (see chapter 4.5.5). For compressed output, this output command may |
|---|
| 62 | remain |
|---|
| 63 | unchanged in the configuration file, since <tt><font |
|---|
| 64 | style="font-size: 10pt;" size="2">combine_plot_fields.x</font></tt> |
|---|
| 65 | recognizes the |
|---|
| 66 | ex<font face="Thorndale, serif">isten</font>ce of <tt><font |
|---|
| 67 | style="font-size: 10pt;" size="2">PLOT3D_COMPRESSED</font></tt> |
|---|
| 68 | and carries out no actions in such cases. </p> |
|---|
| 69 | <p style="line-height: 100%;">The file connection statements for the |
|---|
| 70 | local file <a href="chapter_3.4.html#PLOT3D_DATA">PLOT3D_DATA</a> |
|---|
| 71 | and all further necessary statements to create plots of 3d volume |
|---|
| 72 | data can be found in <a href="chapter_4.5.5.html">chapter |
|---|
| 73 | 4.5.5</a>. </p> |
|---|
| 74 | <p style="line-height: 100%;">After been transferred to the local |
|---|
| 75 | computer |
|---|
| 76 | of the user, the tar file with the compressed data cannot be read |
|---|
| 77 | with the usual <span style="font-weight: bold;">AVS</span> module |
|---|
| 78 | read field. Alternatively, |
|---|
| 79 | the module read_compressed_field particularly developed |
|---|
| 80 | for this purpose must be used. This module is located in a module |
|---|
| 81 | library under: </p> |
|---|
| 82 | <pre style="margin-bottom: 0.5cm; line-height: 100%;"><font |
|---|
| 83 | style="font-size: 10pt;" size="2">http://www.muk.uni-hannover.de/~raasch/PALM_group/AVS/Libraries/palm</font></pre> |
|---|
| 84 | <p style="line-height: 100%;">This module must be loaded within AVS |
|---|
| 85 | (network editor - > module |
|---|
| 86 | tools - > read module library) and then it can be used like all |
|---|
| 87 | other modules. <a |
|---|
| 88 | href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/read_compressed_field.html">Further |
|---|
| 89 | information</a> about using this module is available (e.g. for |
|---|
| 90 | accelerated treatment of compressed data with <span |
|---|
| 91 | style="font-weight: bold;">AVS</span> the module |
|---|
| 92 | <a |
|---|
| 93 | href="http://www.muk.uni-hannover.de/institut/people/raasch/PALM_group/AVS/Doc/write_compressed_field.html">write_compressed_field</a> |
|---|
| 94 | is available). <br> |
|---|
| 95 | <br> |
|---|
| 96 | </p> |
|---|
| 97 | <hr> |
|---|
| 98 | <p style="line-height: 100%;"><br> |
|---|
| 99 | <font color="#000080"><font color="#000080"><a href="chapter_4.5.5.html"><font |
|---|
| 100 | color="#000080"><img src="left.gif" name="Grafik1" align="bottom" |
|---|
| 101 | border="2" height="32" width="32"></font></a><a href="index.html"><font |
|---|
| 102 | color="#000080"><img src="up.gif" name="Grafik2" align="bottom" |
|---|
| 103 | border="2" height="32" width="32"></font></a><a |
|---|
| 104 | href="chapter_4.5.7.html"><font color="#000080"><img src="right.gif" |
|---|
| 105 | name="Grafik3" align="bottom" border="2" height="32" width="32"></font></a></font></font></p> |
|---|
| 106 | <p style="line-height: 100%;"> <i>Last change: </i> 20/04/05 |
|---|
| 107 | (SR)</p> |
|---|
| 108 | </body> |
|---|
| 109 | </html> |
|---|
