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<H1>little-o notation</H1>
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(definition)
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<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) = o(g(n)) means f(n) becomes insignificant relative to g(n) as n approaches infinity. More formally it means for all c > 0, there exists some k > 0 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"> f(n) < cg(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 value of k must not depend on n, but may depend on c.
<P><strong>See also</strong>
<a href="bigOnotation.html" tppabs="http://hissa.nist.gov/dads/HTML/bigOnotation.html"><em>big-O notation</em></a>.
<P><em>Note:
As an example, 3n + 4 is o(n<sup>2</sup>) since for any c we can choose k > (3+ <img src="sqrt.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/sqrt.gif" border=0 height=15 width=12 alt="square root of">(9+16c))/2c. 3n + 4 is not o(n). o(f(n)) is an upper bound which is not <a href="asymptghtbnd.html" tppabs="http://hissa.nist.gov/dads/HTML/asymptghtbnd.html"><em>asymptotically tight</em></a>. <P> Strictly, the character is the lower case Greek letter omicron.</em>
<P>Author: <a href="terms.html#authorPEB" tppabs="http://hissa.nist.gov/dads/terms.html#authorPEB">PEB</a>
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Entry modified Fri Jan 7 09:56:59 2000.<BR>
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