I don't think this idea has been suggested yet: (1) Form all n! n x n permutation matrices, say M_1, ..., M_K, K = n!.
(2) Generate K independent uniform variates x_1, ..., x_k. (3) Renormalize these to sum to 1, x <- x/sum(x) (4) Form the convex combination M = x_1*M_1 + ... + x_K*M_K M is a ``random'' doubly stochastic matrix. The point is that the set of all doubly stochastic matrices is a convex set in n^2-dimensional space, and the extreme points are the permutation matrices. I.e. the set of all doubly stochastic matrices is the convex hull of the the permuation matrices. The resulting M will *not* be uniformly distributed on this convex hull. If you want a uniform distribution something more is required. It might be possible to effect uniformity of the distribution, but my guess is that it would be a hard problem. cheers, Rolf Turner [EMAIL PROTECTED] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.