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132 lines
5.0 KiB
132 lines
5.0 KiB
2 years ago
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<!-------- @HEADER
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!
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! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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!
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! Zoltan Toolkit for Load-balancing, Partitioning, Ordering and Coloring
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! Copyright 2012 Sandia Corporation
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!
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! Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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! the U.S. Government retains certain rights in this software.
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!
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! Redistribution and use in source and binary forms, with or without
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! modification, are permitted provided that the following conditions are
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! met:
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!
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! 1. Redistributions of source code must retain the above copyright
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! notice, this list of conditions and the following disclaimer.
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!
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! 2. Redistributions in binary form must reproduce the above copyright
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! notice, this list of conditions and the following disclaimer in the
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! documentation and/or other materials provided with the distribution.
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!
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! 3. Neither the name of the Corporation nor the names of the
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! contributors may be used to endorse or promote products derived from
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! this software without specific prior written permission.
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!
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! THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
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! EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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! IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
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! CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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! EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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! PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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! PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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! LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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! NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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! SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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!
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! Questions? Contact Karen Devine kddevin@sandia.gov
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! Erik Boman egboman@sandia.gov
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!
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! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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!
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! @HEADER
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------->
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.7 [en] (X11; U; SunOS 5.6 sun4m) [Netscape]">
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<meta name="sandia.approved" content="SAND99-1376">
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<meta name="author" content="karen devine, kddevin@sandia.gov">
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<title> Zoltan Developer's Guide: Hash function</title>
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</head>
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<body bgcolor="#FFFFFF">
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<div align=right><b><i><a href="dev.html">Zoltan Developer's Guide</a>
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| <a href="dev_services_time.html">Next</a> | <a href="dev_services_objlist.html">Previous</a></i></b></div>
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<!------------------------------------------------------------------------->
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<h2>
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Hash Function</h2>
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Zoltan provides a hash function for global and local IDs. The hash function
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computes a non-negative integer value in a certain range<i> </i>from an
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ID.
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<blockquote><b><a href="#Zoltan_Hash">Zoltan_Hash</a></b> : hash a global
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or local ID into non-negative integers</blockquote>
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<!------------------------------------------------------------------------->
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<hr>
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<a NAME="Zoltan_Hash"></a>
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<hr>
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unsigned int<b> Zoltan_Hash</b>(
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<b><a href="../ug_html/ug_usage.html#Data Types for Object IDs">ZOLTAN_ID_PTR
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</a></b><i>key</i>,
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int <i>num_id_entries</i>, unsigned int <i>n</i>);
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<hr>
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<b>Zoltan_Hash </b>computes a hash value for a global or local ID. Note
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that this hash function has been optimized for 32-bit integer systems,
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but should work on any machine. The current implementation uses a
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simple multiplicative hash function based on Don Knuth's golden ratio method;
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see <i>The Art of Computer Programming,</i> vol. 3.
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<br>
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<table WIDTH="100%" >
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<tr VALIGN=TOP>
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<td VALIGN=TOP WIDTH="20%"><b>Arguments:</b></td>
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<td WIDTH="80%"></td>
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</tr>
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<tr VALIGN=TOP>
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<td VALIGN=TOP> <i>key</i></td>
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<td>A pointer to the ID to be hashed.</td>
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</tr>
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<tr VALIGN=TOP>
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<td> <i>num_id_entries</i></td>
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<td>The length of the ID (as given by <b><a href="../ug_html/ug_param.html#NUM_GID_ENTRIES">NUM_GID_ENTRIES</a></b>
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or <b><a href="../ug_html/ug_param.html#NUM_LID_ENTRIES">NUM_LID_ENTRIES</a></b>).</td>
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</tr>
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<tr VALIGN=TOP>
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<td VALIGN=TOP> <i>n</i></td>
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<td>The computed hash value will be between 0 and <i>n</i>-1. </td>
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</tr>
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<tr VALIGN=TOP>
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<td><b>Return Value:</b></td>
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<td></td>
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</tr>
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<tr VALIGN=TOP>
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<td> unsigned int</td>
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<td>The hash value (between 0<i> </i>and <i>n</i>-1). </td>
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</tr>
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</table>
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<p>
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<!------------------------------------------------------------------------->
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<hr WIDTH="100%">
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<br>[<a href="dev.html">Table of Contents</a> | <a href="dev_services_time.html">Next:
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Timing Routines</a> | <a href="dev_services_objlist.html">Previous:
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Object List Function</a> | <a href="https://www.sandia.gov/general/privacy-security/index.html">Privacy and Security</a>]
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</body>
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</html>
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