In the discussion of issue 9804 <https://github.com/JuliaLang/julia/pull/9804#issuecomment-140404574>, the general consensus seemed to be:
> Right. "rref" has no use in real numerical coding, but every use in pedagogy. I had a linear regression yield a PosDefError (the X matrix contains only integers and was singular). I solved it by selecting a linearly independent subset of columns <http://math.stackexchange.com/questions/199125/how-to-remove-linearly-dependent-rows-cols>. This uses the Row-Echelon-Form, rref. Is there a simpler way of doing this that I'm missing? Cédric
