| tr {gRc} | R Documentation |
Calculate trace of various matrix products.
trA(A) trAW(A,W) trAWB(A,W,B) trAWBW(A,W,B) trAWBV(A,W,B,V)
A,B |
Square matrices represented as matrices or lists (see examples below). |
W,V |
Square matrices |
A number
Søren Højsgaard, sorenh@agrsci.dk
d <- 5
W <- matrix(rnorm(d*d),nr=d,nc=d);
V <- W <- W+t(W)
## Turn list into matrix
##
tomat <- function(x){
ans <- do.call("rbind", x)
storage.mode(ans)<-"double"
return(ans)
}
A1 <- tomat(list(c(1,2),c(1,3)))
A2 <- tomat(list(1,3,5))
## Just for checking the calculations
##
symMat <- function(A,d){
ans <- matrix(0,nr=d,nc=d)
for (i in 1:length(A)){
e <- A[[i]]
if (length(e)==1){
ans[e,e] <- 1
} else {
ans[e[1],e[2]] <- ans[e[2],e[1]] <- 1
}
}
return(ans)
}
trAW(A1, W)
#sum(diag(symMat(A1,d=d)
trAW(A2, W)
#sum(diag(symMat(A2,d=d)
trAWB(A1, W, A2)
#sum(diag(symMat(A1,d=d)
trAWBV(A1, W, A2, V)
#sum(diag(symMat(A1,d=d)