This function tests whether a tree is ultrametric using the distances
from each tip to the root.
Usage
is.ultrametric(phy, ...)
"is.ultrametric"(phy, tol = .Machine$double.eps^0.5, option = 1, ...)
"is.ultrametric"(phy, tol = .Machine$double.eps^0.5, option = 1, ...)
Arguments
phy
an object of class "phylo" or "multiPhylo".
tol
a numeric >= 0, variation below this value are considered
non-significant.
option
an integer (1 or 2; see details).
...
arguments passed among methods.
Value
a logical vector.
Details
The test is based on the distances from each tip to the root and a
criterion: if option = 1, the criterion is the scaled range
((max - min/max)), if option = 2, the variance is used (this
was the method used until ape 3.5). The default criterion is invariant
to linear changes of the branch lengths.