AI-GEOSTATS: SUMMARY: Simulating spatial autocorrelation?
Hello all, Yesterday morning I asked for pointers to software and algorithms, preferably MATLAB, that could simulate spatially- autocorrelated and/or fractal 2D patterns. Here is a summary of replies. 1) Brian R Gray [[EMAIL PROTECTED]] suggested simply using PROC SIM2D in SAS. 2) Yetta Jager [[EMAIL PROTECTED]] has used Gstat. Her results are documented at http://www.esd.ornl.gov/~zij/, and Gstat is at http://www.geog.uu.nl/gstat/. 3) W. W. Hargrove [[EMAIL PROTECTED]] suggests that I take a look at the Fractal Realizer (http://research.esd.ornl.gov/realizer). 4) Marc Serre [[EMAIL PROTECTED]] recommends BMElib, which does have the advantage of being MATLAB code. You can find out more about BMElib at http://www.unc.edu/depts/case/BMELIB/. Not being a SAS user, I'm pursuing the latter three, all of which appear likely to be useful to me. Thanks for all responses. regards, Mark A. Dr. Mark C. Andersen, Associate Professor Department of Fishery and Wildlife Sciences Campus Box 4901 New Mexico State University Las Cruces, NM 88003-0003 phone: 505-646-8034 fax: 505-646-1281 -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
Re: AI-GEOSTATS: Negative variances
Kevin There is something badly wrong with your software. With ordinary kriging, it is not possible to get negative variances. With lognormal kriging, it is not possible to get negative varianse or negative estimates unless you are using a large additive constant. Isobel Clark http://uk.geocities.com/drisobelclark --- Kevin Lowe Rfn <[EMAIL PROTECTED]> wrote: > Hi all > > I have been experimenting with various kriging > methods in estimating > Witwatersrand gold grades (South Africa) using > Datamine software. I found > that using lognormal ordinary kriging has resulted > in negative variances in > some blocks. > > My question is why does this happen and what is the > significance of it? > > Kevin Lowe > e-mail [EMAIL PROTECTED] > > -- > * To post a message to the list, send it to > [EMAIL PROTECTED] > * As a general service to the users, please remember > to post a summary of any useful responses to your > questions. > * To unsubscribe, send an email to [EMAIL PROTECTED] > with no subject and "unsubscribe ai-geostats" > followed by "end" on the next line in the message > body. DO NOT SEND Subscribe/Unsubscribe requests to > the list > * Support to the list is provided at http://www.ai-geostats.org Nokia Game is on again. Go to http://uk.yahoo.com/nokiagame/ and join the new all media adventure before November 3rd. -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
