Newbie hung up with matrices
rwatkins at cornerstonelp.com wrote:
I just started learning R. I'm trying to use the Help and the downloadable manuals. I am stuck on trying to multiply matrices. Can anyone please supply a couple of lines of code that I can plug into a fresh console to see how a double precision (1x3) matrix is multiplied by a double precision (3x3) matrix? I keep getting an error message,"Error in x%*%A: requires numeric matrix/vector arguments".
> A <- matrix(c(1,4,7,2,5,8,3,6,9), ncol=3, byrow=TRUE)
> x <- c(3,5,6)
> x%*%A
[,1] [,2] [,3]
[1,] 31 73 115
The result of read.csv is not a matrix, so try the following:
A <- as.matrix(A)
x%*%A
hope this helps,
Chuck Cleland