% TREEWALK: Produce a random tree by a random walk through a p-dimensional space
% via random step-lengths from a Minkowski distribution (for which k=2
% corresponds to a Brownian-motion model). Random walk may be along a
% given tree (specified by an ancestor function and, optionally,
% corresponding branch lengths that are proportional to times between
% cladogenetic events) or produced according to expected times between
% cladogenetic events.
%
% Usage: [w_anc,w_brlen] = trewalk(P,{stepstd},{tmax},{k},{anc},{brlen})
%
% P = dimension of space.
% stepstd = standard deviation of step-lengths along branches
% [default = 1].
% tmax = number of total time-steps for tree [default = 1000].
% k = Minkowski parameter [default = 2].
% anc = ancestor function for specified tree.
% brlen = if 'anc' is given: corresponding branch lengths (time
% durations) for specified tree;
% if 'anc' is not given: 2-element vector of mean and
% standard deviation of expected branch lengths (in time
% steps).
% ------------------------------------------------------------------
% w_anc = ancestor function for resulting tree (same as anc, if
% specified).
% w_brlen = branch lengths of resulting tree.
%
% RE Strauss, 12/26/99
function [w_anc,w_brlen] = trewalk(P,stepstd,tmax,k,anc,brlen)
return;