Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/17/84; site opus.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!hao!nbires!opus!rcd From: rcd@opus.UUCP (Dick Dunn) Newsgroups: net.lang Subject: Re: Efficiency of Languages (and complexity) Message-ID: <196@opus.UUCP> Date: Mon, 4-Nov-85 02:47:01 EST Article-I.D.: opus.196 Posted: Mon Nov 4 02:47:01 1985 Date-Received: Tue, 5-Nov-85 07:22:59 EST References: <15100004@ada-uts.UUCP> <15100007@ada-uts.UUCP> <189@opus.UUCP> <12860@rochester.UUCP> Organization: NBI,Inc, Boulder CO Lines: 29 Talking about sorting and complexity of algorithms... > In article <189@opus.UUCP> rcd@opus.UUCP (Dick Dunn) writes: > ... > >NO! You cannot throw "n different processors" at the array! N is > >(potentially) larger than the number of processors you have... > ... > I am afraid that this opinion is an oversimplification...it is > perfectly reasonable to study the case where the amount of hardware > available is proportional to size of the problem or some function thereof > (like log(n)). This is no more an assumption of infinite hardware > than O(n) assumes that you have infinite time... OK, now I am SURE that the folks who are responding to this don't understand O() notation. This notation is explicitly designed to express the ASYMPTOTIC COMPLEXITY of an algorithm. If that's not what you mean, use some other notation. The usefulness of this sort of complexity measure is that it tells how the required processing time (or space) increases in relation to the "size" of the problem being solved. Again, O() notation is an asymptotic measure. This makes it quite explicit that you cannot have an "...amount of hardware...proportional to size of the problem..." unless you consider an infinite amount of hardware. The "order-of" notation is not the only measure that can be applied to an algorithm--but it DOES have a specific meaning and a specific use, and it's a very basic part of analysis of algorithms. Try to understand it before you use it. -- Dick Dunn {hao,ucbvax,allegra}!nbires!rcd (303)444-5710 x3086 ...Never attribute to malice what can be adequately explained by stupidity.