I posted this earlier, but am not certain that it was in fact posted, so I will try again. Hi, I have an equation Xcp and would like to look at errors affecting it. I am applying errors of -.58 to .1 to R and -.45 to .47 to Xc. I would like to look at all combinations. I set up a matrix function as follows and it does not work. On the last line, when it run, it does not seem like the two X’s are not the same. Example: it is NOT 1+(162/1), but using another “R” value. R<-c(1:5) Xc<-c(16:20) Xcp<-R+((Xc^2)/R) test=R+(Xc^2/R) x=c(-.58, -.44, -.31, -.17, -.04, .1) y=c(-.45,-.27,-.08,.10,.29,.47) actual=Xcp X=((R%o%x+R)) Y=(Xc%o%y+Xc) num.x.col <- length(X[1,]) num.y.col <- length(Y[1,]) num.rows <- length(X[,1]) Z <- matrix(nrow=num.rows, ncol=num.x.col*num.y.col) for( i in 1:num.rows) { Z[i,] <- as.vector(X[i,] + ((Y[i,])^2 %*% t(X[i,])^-1 )) } -- M. Keith Cox, Ph.D. Alaska NOAA Fisheries, National Marine Fisheries Service Auke Bay Laboratories 17109 Pt. Lena Loop Rd. Juneau, AK 99801 Keith.Cox@noaa.gov marlinkcox@gmail.com U.S. (907) 789-6603 -- M. Keith Cox, Ph.D. Alaska NOAA Fisheries, National Marine Fisheries Service Auke Bay Laboratories 17109 Pt. Lena Loop Rd. Juneau, AK 99801 Keith.Cox@noaa.gov marlinkcox@gmail.com U.S. (907) 789-6603 [[alternative HTML version deleted]]