OK I think I have it, sorry to have bothered you: x<-seq(1,2) y<-seq(1,2) z<-seq(1,4) data<-data.frame(x,y,z) x<-unique(data$x) y<-unique(data$y) z<-matrix(data$z,length(y),length(x)) contour(x,y,z,xlab="x", ylab="y") persp(x,y,z, col="gray") Now I just have to look back in my notes to find out how to make this work for 1600 z values--currently R runs out of memory. Bill -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._