## is.ultrametric.R (2009-05-10)
## Test if a Tree is Ultrametric
## Copyright 2003-2009 Emmanuel Paradis
## This file is part of the R-package `ape'.
## See the file ../COPYING for licensing issues.
is.ultrametric <- function(phy, tol = .Machine$double.eps^0.5)
{
if (!inherits(phy, "phylo"))
stop('object "phy" is not of class "phylo".')
if (is.null(phy$edge.length))
stop("the tree has no branch lengths.")
phy <- reorder(phy)
n <- length(phy$tip.label)
n.node <- phy$Nnode
## xx: vecteur donnant la distance d'un
## noeud ou tip à partir de la racine
xx <- numeric(n + n.node)
for (i in 1:dim(phy$edge)[1])
xx[phy$edge[i, 2]] <- xx[phy$edge[i, 1]] + phy$edge.length[i]
if (identical(all.equal.numeric(var(xx[1:n]),
0, tolerance = tol), TRUE)) TRUE
else FALSE
}
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