RFish wrote: > > I new to using R and am struggling with some matrix multiplication. >
I'm not sure what you're trying to print, but you could place this vector in an expression mat3<-expression(c(0,rnorm(1,0.6021,0.0987),0,0,0,0,0,0,0,rnorm(1,0.6021,0.0987),0,0,0,0,1.9,0,0,rnorm(1,0.6021,0.0987),0,0,0,4.8,0,0,0,rnorm(1,0.6021,0.0987),0,0,9.7,0,0,0,0,rnorm(1,0.6021,0.0987),0,18,0,0,0,0,0,rnorm(1,0.6021,0.0987),32.6,0,0,0,0,0,0)) # and then evaluate to get a new matrix each time matrix(eval(mat3), nrow=7) #I think this may be easier to follow. First create a matrix of zeros, stick in fertilities and then add random survival probabilities each time mat3<-diag(0,7) #fertilities mat3[1,3:7]<-c(1.9, 4.8, 9.7, 18, 32.6) # random survival on sub-diagonal mat3[row(mat3)==col(mat3)+1]<-rnorm(6,0.6021,0.0987) # and if you want to project the population over 10 time steps in a loop ? n<-matrix(c(500,0,0,0,0,0,0)) popsize <- matrix(numeric(7 * 10), nrow = 7) for (i in 1:10) { popsize[, i] <- n mat3[row(mat3)==col(mat3)+1]<-rnorm(6,0.6021,0.0987) n <- mat3 %*% n } [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [1,] 500 0.0000 0.0000 531.6256 709.89940 940.19337 1697.52862 3403.6610 [2,] 0 352.5116 0.0000 0.0000 298.97874 424.71160 561.32525 1027.1605 [3,] 0 0.0000 279.8029 0.0000 0.00000 231.45988 316.83352 424.8883 [4,] 0 0.0000 0.0000 147.8957 0.00000 0.00000 136.36804 220.7370 [5,] 0 0.0000 0.0000 0.0000 96.92715 0.00000 0.00000 108.6551 [6,] 0 0.0000 0.0000 0.0000 0.00000 69.87527 0.00000 0.0000 [7,] 0 0.0000 0.0000 0.0000 0.00000 0.00000 65.86229 0.0000 Chris Stubben -- View this message in context: http://www.nabble.com/Matrix-multiplication-and-random-numbers-tp25365184p25369495.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.