📄 theta.html
字号:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD W3 HTML 2.0//EN">
<HTML lang="en-US">
<HEAD>
<TITLE>Theta</TITLE>
<META name="description"
content="Definition of Theta,
possibly with links to more information and implementations.">
<META name="keywords" content="Theta">
</HEAD>
<BODY BGCOLOR="#FFFFFF">
<H1> <img src="Theta-1.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/Theta.gif" border=0 height=10 width=8 alt="Capital Theta"></H1>
<P>
(definition)
<P>
<strong>Definition:</strong>
A theoretical measure of the execution of an <a href="algorithm.html" tppabs="http://hissa.nist.gov/dads/HTML/algorithm.html"><em>algorithm</em></a>, usually the time or memory needed, given the problem size n, which is usually the number of items. Informally, saying some equation f(n) = <img src="Theta-1.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/Theta.gif" border=0 height=10 width=8 alt="Capital Theta"> (g(n)) means it is within a constant multiple of g(n). More formally, it means there are positive constants c<sub>1</sub>, c<sub>2</sub>, and k, such that 0 <img src="leq.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/leq.gif" border=0 height=7 width=14 alt="less than or equal to"> c<sub>1</sub>g(n) <img src="leq.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/leq.gif" border=0 height=7 width=14 alt="less than or equal to"> f(n) <img src="leq.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/leq.gif" border=0 height=7 width=14 alt="less than or equal to"> c<sub>2</sub>g(n) for all n <img src="geq.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/geq.gif" border=0 height=7 width=14 alt="greater than or equal to"> k. The values of c<sub>1</sub>, c<sub>2</sub>, and k must be fixed for the function f and must not depend on n.
<P><strong>See also</strong>
<a href="bigOnotation.html" tppabs="http://hissa.nist.gov/dads/HTML/bigOnotation.html"><em>big-O notation</em></a>, <a href="asymptghtbnd.html" tppabs="http://hissa.nist.gov/dads/HTML/asymptghtbnd.html"><em>asymptotically tight</em></a>.
<P><em>Note:
This is the Greek letter capital Theta.</em>
<P>Author: <a href="terms.html#authorPEB" tppabs="http://hissa.nist.gov/dads/terms.html#authorPEB">PEB</a>
<hr>
Go to the
<A HREF="terms.html" tppabs="http://hissa.nist.gov/dads/terms.html">Algorithms, Data Structures, and Problems</A>
home page.
<hr>
If you have suggestions, corrections, or comments, please get in touch
with
<a href="javascript:if(confirm('http://hissa.nist.gov/~black/black.html \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://hissa.nist.gov/~black/black.html'" tppabs="http://hissa.nist.gov/~black/black.html">Paul E. Black</a>
(<a href="mailto:paul.black@nist.gov">paul.black@nist.gov</a>).
<p>
Entry modified Fri Jan 7 09:57:24 2000.<BR>
HTML page formatted Mon Jan 10 09:20:57 2000.
<P>
This page's URL is
<A href="theta.html" tppabs="http://hissa.nist.gov/dads/HTML/theta.html">http://hissa.nist.gov/dads/HTML/theta.html</A>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -