swh:1:snp:a4c99a50dc49f82b591f268001b320f8c3ca0041
Tip revision: ce60f670aac0a708d3a9af5f0cf46a752d46ba8a authored by John M Chambers on 28 October 2020, 07:59:48 UTC
version 1.0-6.1
version 1.0-6.1
Tip revision: ce60f67
triDiagonal.R
## extra triDiag functions
triDiag2S <- function(diagonal, upper, lower, r = length(diagonal)) {
value <- diag(diagonal, r)
if(r > 1) {
rseq <- 1:(r-1)
index <- cbind(rseq+1, rseq)
value[index] <- lower
index <- cbind(rseq, rseq+1)
value[index] <- upper
}
value
}
triDiag3S <- function(diagonal, upper, lower,
r = length(diagonal)) {
value <- matrix(0, r, r)
if(r > 0) {
r1 <- r-1
index <- outer((0:r1)*(r+1), 0:2, "+")
value[index[,2]] <- diagonal
value[index[-1, 1]] <- upper
value[index[-r, 3]] <- lower
}
value
}