Re: Norm
- To: mathgroup at smc.vnet.net
- Subject: [mg68000] Re: [mg67973] Norm
- From: "Carl K. Woll" <carlw at wolfram.com>
- Date: Thu, 20 Jul 2006 06:04:42 -0400 (EDT)
- References: <200607190921.FAA21393@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Clausenator at gmail.com wrote: > Hi, > I want to calculate a distance matrix, similar to (as poorly explained > at) http://en.wikipedia.org/wiki/Distance_matrix > > I found out about the Function "Norm" in mathematica 5. > > Here is a little example. I want to calculate the distance between > vectors {0,1} and {5,1}. The distance should be 5 > > Now, > > Norm[{{0., 1.}, {5., 1.}}, 2] > results 5.10293 > Here you are computing the 2-norm of a matrix. > Norm[{{0., 1.} - {5., 1.}}, 2] > results 5.0 > Here you are computing the 2-norm of a vector. The norms of a matrix and a vector are not the same thing. Since you are interested in the distance between two points, you want to compute the magnitude of the difference of the two points, so you want to evaluate the norm of point1 minus point2. Carl Woll Wolfram Research > According to the documentation I have (Mathematica Help Browser, search > for "Norm" under "Built-in Functions") the version with the comma is > documented. I like the solution with the dash better. > Which one is it? In other words, is there some Wolfram description or > can you explain the difference? > > Thanks for your help, > Claus
- References:
- Norm
- From: Clausenator@gmail.com
- Norm