With the default value of fun
, this function calculates
for each pair of columns of x
the mean of the absolute values
of their differences (which is proportional to the L1-norm of their
difference). This is a distance metric. The implementation assumes that
fun(x[,i], x[,j])
can be evaluated for all pairs of i
and j
(see examples), and that
fun
is symmetric, i.e.
fun(a, b) = fun(b, a)
.
fun(a, a)
is not actually evaluated, instead the value of diagonal
is used to fill the diagonal elements of the returned matrix.
Note that dist
computes distances between rows of
x
, while this function computes relations between columns of
x
(see examples).