Same as lower.tri()
except it returns the values from the matrix (rather than a positional
matrix that lets you look up the values).
lower_tri(x, diag = FALSE)
The values in the lower triangular part of the matrix.
a matrix or other R object with length(dim(x)) == 2
.
For back compatibility reasons, when the above is not fulfilled,
as.matrix(x)
is called first.
logical. Should the diagonal be included?