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<html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><!--Converted with jLaTeX2HTML 2002 (1.62) JA patch-1.4patched version by: Kenshi Muto, Debian Project.LaTeX2HTML 2002 (1.62),original version by: Nikos Drakos, CBLU, University of Leeds* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan* with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --><HTML><HEAD><TITLE>4.2.5 Precision of the scheduler clock used in ns</TITLE><META NAME="description" CONTENT="4.2.5 Precision of the scheduler clock used in ns"><META NAME="keywords" CONTENT="everything"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"><META NAME="Generator" CONTENT="jLaTeX2HTML v2002 JA patch-1.4"><META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"><LINK REL="STYLESHEET" HREF="everything.css" tppabs="http://www.isi.edu/nsnam/ns/doc/everything.css"><LINK REL="previous" HREF="node36.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node36.html"><LINK REL="up" HREF="node32.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node32.html"><LINK REL="next" HREF="node38.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node38.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html1883" HREF="node38.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node38.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html1877" HREF="node32.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node32.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html1873" HREF="node36.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node36.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html1879" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html1881" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html1884" HREF="node38.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node38.html">4.3 Other Methods</A><B> Up:</B> <A NAME="tex2html1878" HREF="node32.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node32.html">4.2 Schedulers and Events</A><B> Previous:</B> <A NAME="tex2html1874" HREF="node36.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node36.html">4.2.4 The Real-Time Scheduler</A>   <B> <A NAME="tex2html1880" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html1882" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H2><A NAME="SECTION03125000000000000000"></A><A NAME="sec:precision"></A><BR>4.2.5 Precision of the scheduler clock used in ns</H2><P>Precision of the scheduler clock can be defined as the smallest time-scale of the simulator that can be correctly represented. The clock variable for ns is represented by a double. As per the IEEE std for floating numbers, a double, consisting of 64 bits must allocate the following bits between its sign, exponent and mantissa fields.<P><PRE>sign exponent mantissa 1 bit 11 bits 52 bits</PRE><P>Any floating number can be represented in the form () where X is the mantissa and n is the exponent. Thus the precision of timeclock in ns can be defined as ().As simulation runs for longer times the number of remaining bits to represent the time educes thus reducing the accuracy. Given 52 bits we can safely say time upto around () can be represented with considerable accuracy. Anything greater than that might not be very accurate as you have remaining 12 bits to represent the time change. However () is a very large number and we donot anticipate any problem regarding precision of time in ns.<P><HR><!--Navigation Panel--><A NAME="tex2html1883" HREF="node38.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node38.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html1877" HREF="node32.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node32.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html1873" HREF="node36.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node36.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html1879" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html1881" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html1884" HREF="node38.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node38.html">4.3 Other Methods</A><B> Up:</B> <A NAME="tex2html1878" HREF="node32.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node32.html">4.2 Schedulers and Events</A><B> Previous:</B> <A NAME="tex2html1874" HREF="node36.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node36.html">4.2.4 The Real-Time Scheduler</A>   <B> <A NAME="tex2html1880" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html1882" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <!--End of Navigation Panel--><ADDRESS>2003-09-23</ADDRESS></BODY></HTML>⌨️ 快捷键说明
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