EVOLUTION-MANAGER

Edit File: udunits2.html

<html lang="en">
<head>
<title>UDUNITS 2.2.20 Manual</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="UDUNITS 2.2.20 Manual">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="top" href="#Top">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--

This software was developed by the Unidata Program Center of the
University Corporation for Atmospheric Research (UCAR)
<http://www.unidata.ucar.edu>.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

1) Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
   2) Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
   3) Neither the names of the development group, the copyright holders, nor the
      names of contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.
   4) This license shall terminate automatically and you may no longer exercise
      any of the rights granted to you by this license as of the date you
      commence an action, including a cross-claim or counterclaim, against
      the copyright holders or any contributor alleging that this software
      infringes a patent. This termination provision shall not apply for an
      action alleging patent infringement by combinations of this software with
      other software or hardware.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS
OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.
-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"></style>
</head>
<body>
<h1 class="settitle">UDUNITS 2.2.20 Manual</h1>
<div class="contents">
<h2>Table of Contents</h2>
<ul>
<li><a name="toc_Top" href="#Top">UDUNITS-2</a>
<li><a name="toc_Introduction" href="#Introduction">1 Introduction</a>
<li><a name="toc_Differences" href="#Differences">2 How This Package Differs from the Original <code>UDUNITS</code> Package</a>
<li><a name="toc_Installation" href="#Installation">3 Installing this Package</a>
<ul>
<li><a href="#Binary">3.1 Installing from a Binary Distribution</a>
<ul>
<li><a href="#Binary">3.1.1 64-bit CentOS 6.4</a>
<li><a href="#Binary">3.1.2 32-bit Ubuntu 12</a>
</li></ul>
<li><a href="#Source">3.2 Installing from a Source Distribution</a>
<ul>
<li><a href="#Prerequisites">3.2.1 Prerequisites for This Package</a>
<li><a href="#Obtain">3.2.2 Obtaining this Package</a>
<li><a href="#Unix">3.2.3 Unix Installation Instructions</a>
<ul>
<li><a href="#Autoconf">3.2.3.1 Autoconf-based Installation</a>
<li><a href="#CMake">3.2.3.2 CMake-based Installation</a>
</li></ul>
<li><a href="#Windows">3.2.4 Windows Installation Instructions</a>
</li></ul>
</li></ul>
<li><a name="toc_Library" href="#Library">4 Unit Library</a>
<li><a name="toc_Utility" href="#Utility">5 Unit Utility</a>
<li><a name="toc_Database" href="#Database">6 The Units Database</a>
<li><a name="toc_Support" href="#Support">7 Support for this Package</a>
<li><a name="toc_Complete-Index" href="#Complete-Index">Index</a>
</li></ul>
</div>

<div class="node">
<a name="Top"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Introduction">Introduction</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#dir">(dir)</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#dir">(dir)</a>

</div>

<h2 class="unnumbered">UDUNITS-2</h2>

<p>This manual describes the UDUNITS-2 package, which contains
a C library for units of physical quantities and a unit-definition
and value-conversion utility.

<p>This software was developed by the Unidata Program Center of the
University Corporation for Atmospheric Research (UCAR)
&lt;http://www.unidata.ucar.edu&gt;.

<p>Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

<p>1) Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer. 
   2) Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution. 
   3) Neither the names of the development group, the copyright holders, nor the
      names of contributors may be used to endorse or promote products derived
      from this software without specific prior written permission. 
   4) This license shall terminate automatically and you may no longer exercise
      any of the rights granted to you by this license as of the date you
      commence an action, including a cross-claim or counterclaim, against
      the copyright holders or any contributor alleging that this software
      infringes a patent. This termination provision shall not apply for an
      action alleging patent infringement by combinations of this software with
      other software or hardware.

<p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS
OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.

<ul class="menu">
<li><a accesskey="1" href="#Introduction">Introduction</a>:         Introduction
<li><a accesskey="2" href="#Differences">Differences</a>: 		    How this package differs from the UDUNITS-1 package
<li><a accesskey="3" href="#Installation">Installation</a>:         Installing this package
<li><a accesskey="4" href="#Library">Library</a>:              The unit library
<li><a accesskey="5" href="#Utility">Utility</a>:              The unit utility
<li><a accesskey="6" href="#Database">Database</a>:             The unit database
<li><a accesskey="7" href="#Support">Support</a>:              Support for this package
<li><a accesskey="8" href="#Complete-Index">Complete Index</a>:       Complete index
</ul>

<div class="node">
<a name="Introduction"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Differences">Differences</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Top">Top</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">1 Introduction</h2>

<p><a name="index-Introduction-1"></a>
The UDUNITS-2 package provides support for units of physical quantities. 
Its three main components are: 1) <a href="udunits2lib.html#Top">a C library</a>
for units of physical quantities;
2) <a href="udunits2prog.html#Top">a utility</a>;
for obtaining the definition of a unit and for
converting numeric values between compatible units;
and 3) an <a href="#Database">extensive database of units</a>.

<div class="node">
<a name="Differences"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Installation">Installation</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Introduction">Introduction</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">2 How This Package Differs from the Original <code>UDUNITS</code> Package</h2>

<p>The <code>UDUNIT-2</code> package differs from the <code>UDUNITS-1</code>
package in the following ways:
     <ul>
<li><strong>Support for non-ASCII characters:</strong>
The <code>UDUNITS-1</code>
package only supports the ASCII character set.  The <code>UDUNITS-2</code>
package supports the following character sets: ASCII, ISO 8859-1 (Latin-1),
and the UTF-8 encoding of ISO 10646 (Unicode).  This means that unit
string specifications like "<code>µ°F·Ω⁻¹</code>" are now supported (your
viewer must support UTF-8 to display this string correctly).

<li><strong>Support for logarithmic units:</strong>  The unit string
specification "<code>0.1 lg(re 1 mW)</code>" specifies a deciBel unit with a
one milliwatt reference level. 
Such units are fully integrated into the package and all meaningful
operations and conversions are supported.

<li><strong>Persistent value converters:</strong>
It is now possible to obtain a <em>converter</em> data-object, which can
be used to convert numeric values in one unit to numeric values in another,
compatible unit.  The values can be <code>float</code>, <code>double</code>, or
one-dimensional arrays of <code>float</code>s or <code>double</code>s.

<li><strong>Improved API:</strong>  Due to the above changes, it was not
possible to keep the application programming interface (API) of the
<code>UDUNITS-1</code> package.  The new interface, however, is easily
understood and easy to use.  To support backward comptibility,
the package does contain a version 1 C API, which uses the version 2
library.

<li><strong>XML unit database:</strong>  The unit database is encoded using
human-readable XML rather than a custom format.  The XML
parser included in the package supports an <em>&lt;import&gt;</em> element to
allow easy and convenient customization.

<li><strong>No Fortran or Perl API:</strong>  Interfaces for these languages
have not yet been created.  Contact
<a href="mailto:support-udunits@unidata.ucar.edu">support-udunits@unidata.ucar.edu</a> if you are interested in
helping to create these interfaces.

</ul>

<p>One thing that has not changed is that almost all unit string specifications
understood by the <code>UDUNITS-1</code> package are also
understood by the <code>UDUNITS-2</code> package.  One exception is
the symbol <code>g</code>, which in version 1 of the package was associated with
standard free fall (a unit of accelleration) but which is associated
with the unit gram in version 2 of the package.

<div class="node">
<a name="Installation"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Library">Library</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Differences">Differences</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">3 Installing this Package</h2>

<ul class="menu">
<li><a accesskey="1" href="#Binary">Binary</a>:               Installing from a binary distribution
<li><a accesskey="2" href="#Source">Source</a>:               Installing from a source distribution
</ul>

<div class="node">
<a name="Binary"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Source">Source</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Installation">Installation</a>

</div>

<h3 class="section">3.1 Installing from a Binary Distribution</h3>

<h4 class="subsection">3.1.1 64-bit CentOS 6.4</h4>

<p>If your operating system is compatible with 64-bit CentOS 6.4 (e.g., your system
is 64-bit CentOS, Fedora, or RedHat), then create the file
<code>/etc/yum.repos.d/unidata.repo</code> with the following contents:

<pre class="example">     [unidata]
     name=Unidata Repository
     baseurl=http://www.unidata.ucar.edu/repos/yum/CentOS/6/$basearch
     enabled=1
</pre>
   <p>You should then be able to install this package in the usual manner. 
For example,

<pre class="example">     su -
     yum install udunits
</pre>
   <h4 class="subsection">3.1.2 32-bit Ubuntu 12</h4>

<p>If your operating system is compatible with 32-bit Ubuntu 12 (precious pangolin)
(e.g., your system is 32-bit Debian or Ubuntu), then add the following line to
the file <code>/etc/apt/sources.list</code> or
<code>/etc/apt/sources.list.d/unidata.list</code>:

<pre class="example">     deb http://www.unidata.ucar.edu/repos/apt i386/
</pre>
   <p>You should then be able to install this package in the usual manner. 
For example,

<pre class="example">     su -
     apt-get update
     apt-get install udunits
</pre>
   <div class="node">
<a name="Source"></a>
<p><hr>
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Binary">Binary</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Installation">Installation</a>

</div>

<h3 class="section">3.2 Installing from a Source Distribution</h3>

<ul class="menu">
<li><a accesskey="1" href="#Prerequisites">Prerequisites</a>:        Prerequisites for this package
<li><a accesskey="2" href="#Obtain">Obtain</a>:               Obtaining this package
<li><a accesskey="3" href="#Unix">Unix</a>:                 Installing on Unix-like environments
<li><a accesskey="4" href="#Windows">Windows</a>:              Installing on Windows environments
</ul>

<div class="node">
<a name="Prerequisites"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Obtain">Obtain</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Source">Source</a>

</div>

<h4 class="subsection">3.2.1 Prerequisites for This Package</h4>

<p><a name="index-prerequisites-for-this-package-5"></a>
The Expat library and header-files must be installed. Look for the library
"libexpat" and the header-file "expat.h".

<p>If this package is to be tested (which is optional), then the CUnit library
and header-files must be installed. Look for the library "libcunit" and the
header-files "CUnit/CUnit.h" and "CUnit/Basic.h".

<p>If this package is to be built on a Windows system, then the CMake and MinGW
packages must be installed. Look for the utility "cmake" and the
directory/folder "MinGW".

<div class="node">
<a name="Obtain"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Unix">Unix</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Prerequisites">Prerequisites</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Source">Source</a>

</div>

<h4 class="subsection">3.2.2 Obtaining this Package</h4>

<p><a name="index-obtaining-this-package-6"></a>
Get the source for this package from its download-page at
<a href="ftp://ftp.unidata.ucar.edu/pub/udunits/">ftp://ftp.unidata.ucar.edu/pub/udunits/</a>
and unpack it in an appropriate place. For example,

<pre class="example">     su -
     cd /usr/local/src
     wget -O - ftp://ftp.unidata.ucar.edu/pub/udunits/udunits-2.2.20-Source.tar.gz |
     gunzip -c | pax -r
</pre>
   <div class="node">
<a name="Unix"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Windows">Windows</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Obtain">Obtain</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Source">Source</a>

</div>

<h4 class="subsection">3.2.3 Unix Installation Instructions</h4>

<ul class="menu">
<li><a accesskey="1" href="#Autoconf">Autoconf</a>:     Autoconf-based installation
<li><a accesskey="2" href="#CMake">CMake</a>:        CMake-based installation
</ul>

<div class="node">
<a name="Autoconf"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#CMake">CMake</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Unix">Unix</a>

</div>

<h5 class="subsubsection">3.2.3.1 Autoconf-based Installation</h5>

<p>Short instructions:

<pre class="example">     ./configure [--prefix=<var>root</var>] [--disable-shared] [CC=<var>path</var>]
     make
     make check                      # optional; requires CUNIT installation
     make install                    # also installs INFO documentation
     make install-html install-pdf   # optional
     make clean
</pre>
   <p>By default, the installation root is <code>/usr/local</code>.

<p>Long instructions:

<ol type=1 start=1>
<li>Go to the top-level source-directory of this package, e.g.,
     <pre class="example">          cd udunits-2.2.20
</pre>
     <li>If necessary, clean-up from a previous installation attempt by making
the <code>distclean</code> target using the <var>make</var> utility from step 2:
     <pre class="example">          <var>make</var> distclean
</pre>
     <p>The option <code>--disable-shared</code> causes the build process to create
a static library only: a sharable library is not created. 
This option is necessary if the <code>libtool</code> utility that's included
in this package can't build a sharable library using the given compiler.

<li>Execute the <code>configure</code> script. 
Specify the installation prefix, the compiler from the
previous step, and any required option. 
For example, if you are on an HP-UX system and want to use
the <code>/bin/c89</code> compiler and install under <code>/opt</code>,
then the following command is appropriate:

<pre class="example">          ./configure --prefix=/opt --disable-shared CC=/bin/c89
</pre>
     <p>If the installation prefix is not specified, then the default
is to install under <code>/usr/local</code>.

<p>If the compiler isn't specified, then the default is to use
<code>gcc</code>.

<li>Build this package by making the default target using the <var>make</var> utility
from step 2:
     <pre class="example">          <var>make</var>
</pre>
     <li>If you wish to verify that this package works correctly,
then make the <code>check</code> target using the
<var>make</var> utility from step 2:
     <pre class="example">          <var>make</var> check
</pre>
     <p>This step is only effective if the <code>configure</code> script found an
installed <code>CUNIT</code> unit-testing package.  If that package wasn't
found, then the above command will quickly exit without testing this
package.

<li>Install the <a href="udunits2lib.html#Top">library</a>,
<a href="udunits2prog.html#Top">utility</a>, header-files, units-database, and
INFO documentation files by making
the <code>install</code> target using the <var>make</var> utility from
step 2:
     <pre class="example">          <var>make</var> install
</pre>
     <li>If desired, install the HTML and PDF documentation files by making
one or more of the following targets
using the <var>make</var> utility from step 2:
     <pre class="example">          <var>make</var> install-html install-pdf
</pre>
     <li>Clean up by making the <code>clean</code> target using the <var>make</var> utility
from step 2:
     <pre class="example">          <var>make</var> clean
</pre>
     </ol>

<div class="node">
<a name="CMake"></a>
<p><hr>
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Autoconf">Autoconf</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Unix">Unix</a>

</div>

<h5 class="subsubsection">3.2.3.2 CMake-based Installation</h5>

<pre class="example">     cmake
     make all [test] install [install_test]
</pre>
   <p>where the arguments in square brackets are optional.

<div class="node">
<a name="Windows"></a>
<p><hr>
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Unix">Unix</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Source">Source</a>

</div>

<h4 class="subsection">3.2.4 Windows Installation Instructions</h4>

<p>Currently, only a 32-bit <a href="http://www.mingw.org">MinGW</a>-based installation is
supported:

<pre class="example">     cmake -G "MinGW Makefiles"
     cmake --build . [-DCMAKE_INSTALL_PREFIX=<em>dir</em>] -- all [test] install [install_test]
</pre>
   <p>where arguments in square brackets are optional.

<p>The default installation-prefix is
"<code>C:\Program Files (x86)\udunits-2.</code><var>minor</var>.<var>bug</var>", where
<var>minor</var> and <var>bug</var> are the minor version and bug-fix level,
respectively.

<div class="node">
<a name="Library"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Utility">Utility</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Installation">Installation</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">4 Unit Library</h2>

<p><a name="index-Library_002c--unit-7"></a>See <a href="udunits2lib.html#UDUNITS-Library">UDUNITS Library</a>, for details on this package's unit library.

<div class="node">
<a name="Utility"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Database">Database</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Library">Library</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">5 Unit Utility</h2>

<p><a name="index-Utility_002c--unit-8"></a>See <a href="udunits2prog.html#UDUNITS-Utility">UDUNITS Utility</a>, for details on this package's unit
utility.

<div class="node">
<a name="Database"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Support">Support</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Utility">Utility</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">6 The Units Database</h2>

<p><a name="index-database-9"></a>
The database for the UDUNITS-2 package comprises one XML file containing
unit prefixes and four XML files containing unit definitions:

<ul>
<li><a href="../../udunits/udunits2-prefixes.xml">SI unit prefixes</a>
<li><a href="../../udunits/udunits2-base.xml">SI base units</a>
<li><a href="../../udunits/udunits2-derived.xml">SI derived units</a>
<li><a href="../../udunits/udunits2-accepted.xml">Units accepted for use with the SI</a>
<li><a href="../../udunits/udunits2-common.xml">Non-SI units</a>
</ul>

<div class="node">
<a name="Support"></a>
<p><hr>
Next:&nbsp;<a rel="next" accesskey="n" href="#Complete-Index">Complete Index</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Database">Database</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="chapter">7 Support for this Package</h2>

<p><a name="index-support-10"></a><a name="index-package_002c-support-11"></a>
The home-page for this package can be found at
<a href="http://www.unidata.ucar.edu/software/udunits/">http://www.unidata.ucar.edu/software/udunits/</a>.

<p>Bug reports should be sent to
<a href="mailto:support-udunits@unidata.ucar.edu">support-udunits@unidata.ucar.edu</a>.

<div class="node">
<a name="Complete-Index"></a>
<p><hr>
Previous:&nbsp;<a rel="previous" accesskey="p" href="#Support">Support</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>

</div>

<h2 class="unnumbered">Index</h2>

<ul class="index-cp" compact>
<li><a href="#index-database-9">database</a>: <a href="#Database">Database</a></li>
<li><a href="#index-installation-2">installation</a>: <a href="#Installation">Installation</a></li>
<li><a href="#index-Installation_002c-binary-3">Installation, binary</a>: <a href="#Binary">Binary</a></li>
<li><a href="#index-Installation_002c-source-4">Installation, source</a>: <a href="#Source">Source</a></li>
<li><a href="#index-Introduction-1">Introduction</a>: <a href="#Introduction">Introduction</a></li>
<li><a href="#index-Library_002c--unit-7">Library,  unit</a>: <a href="#Library">Library</a></li>
<li><a href="#index-obtaining-this-package-6">obtaining this package</a>: <a href="#Obtain">Obtain</a></li>
<li><a href="#index-package_002c-support-11">package, support</a>: <a href="#Support">Support</a></li>
<li><a href="#index-prerequisites-for-this-package-5">prerequisites for this package</a>: <a href="#Prerequisites">Prerequisites</a></li>
<li><a href="#index-support-10">support</a>: <a href="#Support">Support</a></li>
<li><a href="#index-Utility_002c--unit-8">Utility,  unit</a>: <a href="#Utility">Utility</a></li>
   </ul></body></html>