Path: news.mathworks.com!not-for-mail
From: <HIDDEN>
Newsgroups: comp.soft-sys.matlab
Subject: Re: urgent help in " calcualting number of free independent path"
Date: Mon, 20 Jul 2009 13:11:01 +0000 (UTC)
Organization: The MathWorks, Inc.
Lines: 24
Message-ID: <h41qd5$i02$1@fred.mathworks.com>
References: <gitp09$jh2$1@fred.mathworks.com> <h41mot$gkq$1@fred.mathworks.com>
Reply-To: <HIDDEN>
NNTP-Posting-Host: webapp-02-blr.mathworks.com
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Trace: fred.mathworks.com 1248095461 18434 172.30.248.37 (20 Jul 2009 13:11:01 GMT)
X-Complaints-To: news@mathworks.com
NNTP-Posting-Date: Mon, 20 Jul 2009 13:11:01 +0000 (UTC)
X-Newsreader: MATLAB Central Newsreader 1895050
Xref: news.mathworks.com comp.soft-sys.matlab:556801


I'm not sure what the difference is between an arc-node adjacency matrix and a node-arc connectivity matrix, and I'm at work right now so I can't spend time looking this up.  But since your arc-node adjacency matrix (which seems to be your input) has -1 in it, it is not just the standard adjacency matrix of a directed graph.  So Ray's solution of raising the matrix to a power will not work.

"Ray " <removethis_ray@aarden.us> wrote in message <h41mot$gkq$1@fred.mathworks.com>...
> Ayman,
> 
> The number of paths from one node to another can be obtained through linear graph theory.  Multiply the adjacency matrix times itself (A^2) and you will see the number of paths of length 2 between each pair of nodes ij.  Multiply the adjacency matrix by itself n times (A^n) to find the number of paths of length n between each pair of nodes ij.
> 
> Ref:  http://oneweb.utc.edu/~Christopher-Mawata/petersen/lesson7.htm
> 
> Ray
> _________________
> "ayman ayad" <sea_dreamer82@yahoo.com> wrote in message <gitp09$jh2$1@fred.mathworks.com>...
> > i have a network "water pipe netwrok " 
> > and i have the "connectivity matrix "  bwteen points
> > and i know the id of source points 
> > 
> > does anyone know a file m-file or a way where i can claculate 
> > free independent path , or number of possible paths between source points and any point in the network  
> > so i  can have at the end a digit equall to that number of paths ??
> > 
> > i really need that help so so so much in my Msc 
> > 
> > so if anyone can help me with that i will be so greatful 
> > also u can send me  in my e-mail  sea_dreamer82@yahoo.com