[R] Centered difference operation on matrix with R

[Pascal Oettli]

Dear list members,

I am wondering whether there is any more efficient way to calculate
centered difference on matrix in R? Please see herewith an example:

lon <- matrix(rep(seq(0,2,length.out=1e3), 1e3), 1e3, 1e3)
lat <- matrix(rep(seq(0,2,length.out=1e3), each=1e3), 1e3, 1e3)
x <- matrix(rep(seq(0.01,2,length.out=1e3), 1e3), 1e3, 1e3)
y <- matrix(rep(seq(0.01,2,length.out=1e3), each=1e3), 1e3, 1e3)
u <- y * cos(x)
v <- y * sin(x)

to.rad <- pi/180
dx <- diff(lon,2); dx <- rbind(NA,dx,NA); dx <- dx*to.rad
dy <- t(diff(t(lat),2)); dy <- cbind(NA,dy,NA); dy <- dy*to.rad

du <- t(diff(t(u * cos(lat*to.rad)),2)); du <- cbind(NA,du,NA)
dv <- diff(v,2); dv <- rbind(NA,dv,NA)

Best Regards,
Pascal Oettli