Path: news.mathworks.com!not-for-mail From: "Andrew" <joeblow@aol.com> Newsgroups: comp.soft-sys.matlab Subject: A stupid question about divergence and curl Date: Thu, 2 Apr 2009 04:52:01 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 18 Message-ID: <gr1g9h$hba$1@fred.mathworks.com> Reply-To: "Andrew" <joeblow@aol.com> 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 1238647921 17770 172.30.248.37 (2 Apr 2009 04:52:01 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Thu, 2 Apr 2009 04:52:01 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 894530 Xref: news.mathworks.com comp.soft-sys.matlab:529587 The documentation about divergence and curl is unclear (to me) about what values, and even functions, these operations are evaluated at. For example when I use this code: x=-3:.1:3;y=-3:.1:3; z=exp(-(x.^2+y.^2)); [X Y]=meshgrid(x.*z,y.*z); [U V]=randn(61,61); div=divergence[X,Y,U,V] I get a set of values for the variable "div" that I assume is the divergence of something, but I can't tell what. Then, I change the values of U and V to: [U V]=meshgrid(x,y); div=divergence[X,Y,U,V] I get a different set of values. However, neither of these evaluates the divergence of the vector function [X Y] at the point indicated in [U V]. Is not this what this command is supposed to do? Does anybody know the proper syntax? Thank You for Responding: Andrew Stallard