Does Sage have a function that generates a random double stochastic matrix in which the elements of each row and each column add to one?

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There is a theorem that says that every doubly stochastic matrix is a linear combination of permutation matrices.

If you want random stochastic matrices, generate random linear combinations of permutations. See where that gets you.

It is called the Birkhoff Von Neumann theorem, by the way.

And there is this, too:

http://www.sagemath.org/doc/reference...

Nathann