+\seealso{
+ \code{\link{nj}}, \code{\link{bionj}}, \code{\link{triangMtds}}
+}
+\examples{
+data(woodmouse)
+d <- dist.dna(woodmouse)
+dm <- d
+dm[sample(length(dm), size = 3)] <- NA
+dist.topo(njs(dm), nj(d)) # often 0
+dm[sample(length(dm), size = 10)] <- NA
+dist.topo(njs(dm), nj(d)) # sometimes 0
+}