Both vorticity and divergence are defined in terms of partial derivatives. You can compute these derivatives using the `grad' function in "numDeriv" package.
U <- function(X) { your U function} V <- function(X) { your V function} # where X = c(x,y) library(numDeriv) grU <- function(X) grad(X, func=U) grV <- function(X) grad(X, func=V) # For a 2-dimensional vector field vortivcity <- function(X) grV(X)[2] - grU(X)[1] divergence <- function(X) grU(X)[1] + grV(X)[2] # Here is an example: U <- function(X) X[1]^2 + X[1] * X[2] V <- function(X) X[2]^2 - X[1] * X[2] > vorticity(c(2,1)) [1] -5 > divergence(c(2,1)) [1] 5 > Does this help? Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: [EMAIL PROTECTED] Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ---------------------------------------------------------------------------- -------- -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Igor Oliveira Sent: Monday, September 08, 2008 11:37 AM To: r-help@r-project.org Subject: [R] Vorticity and Divergence Hi all, I have some wind data (U and V components) and I would like to compute Vorticity and Divergence of these fields. Is there any R function that can easily do that? Thanks in advance for any help Igor Oliveira CSAG, Dept. Environmental & Geographical Science, University of Cape Town, Private Bag X3, Rondebosch 7701. Tel.: +27 (0)21 650 5774 South Africa Fax: +27 (0)21 650 5773 http:///www.csag.uct.ac.za/~igor ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.