I have 3 vectors x,y,z: x<-c(-2.88,-1.92,-.96,0,.96,1.92,2.88,3.84, -1.92,-.96,0,.96,1.92,2.88,3.84, -.96,0,.96,1.92,2.88,3.84, 0,.96,1.92,2.88,3.84, .96,1.92,2.88,3.84, 1.92,2.88,3.84, 2.88,3.84, 3.84) y<-c(rep(-3.84,8), rep(-2.88,7), rep(-1.92,6), rep(-.96,5), rep(0,4), rep(.96,3), rep(1.92,2), 2.88) z<-c(.65,1.78,2.4,2.54,3.04,2.22,2.97,3.56, .745,1.287,1.98,1.91,2.02,2.24,2.95, .47,.80,.90,1.32,1.57,2.51, .23,.51,1.38,2.09,2.74, .14,.88,1.87,2.84, .40,1.61,2.48, .78,1.93, .87) These data sample one triangular corner of a matrix. I want a plot of the efficiency zideal<- abs(x-y)/.3 eff<- (z/zideal)^2 But I can't figure out how to get a persp() plot of eff; this doesn't work: persp(x,y,eff,col="grey",theta=45,phi=30) I tried a trick using unique(x),unique(y) which didn't work. If I define x, y and z like this: x<-c(-1.92,-1.44,-.96,-.48,0,.48,.96,1.44,1.92) y<-x z<-rbind(c(NA,.23,.98,1.90,3.60,2.70,3.2,4.11,4.03), c(NA,NA,.39,1.24,3.85,2.40,2.89,3.26,3.92), c(NA,NA,NA,.56,3.26,2.14,2.37,2.67,3.16), c(NA,NA,NA,NA,2.65,1.02,2.08,2.18,2.96), c(NA,NA,NA,NA,NA,2.88,3.45,3.97,3.97), c(NA,NA,NA,NA,NA,NA,.92,1.10,1.90), c(NA,NA,NA,NA,NA,NA,NA,.33,1.02), c(NA,NA,NA,NA,NA,NA,NA,NA,.26), c(NA,NA,NA,NA,NA,NA,NA,NA,NA)) persp(x,y,z,col="grey",theta=45,phi=30, zlim=c(0,7)) persp works. However I don't know how to get a plot of eff, since I don't know how to get eff when z has this form. So please either tell me how to get a persp plot of x,y,z when in the form x<- x1,x2,...xn y<-y1,y2,...yn z<-z1,z2,...zn OR tell me how to get the eff matrix from vectors x and y (short) and matrix z. Thanks very much for any help! Bill Simpson -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._