down.sample(x, factor=2, offset=1) up.sample(x, facter)
down.sample only, a positive integer as the starting index.
down.sample returns a vector of length
[(length(x)-offset+1)/factor];
up.sample
returns a vector of length
length(x)*factor.
down.sample operator decimates
x by a
factor and
up.sample
operator repeats each value in
x by
factor times.