message: ENH: propagate tolerance to lu.Factor()
  Propagate the specified tolerance in LinearSolve() to the
  lu.Factor() call.
diff: @@ -3115,7 +3115,7 @@ bool LinearSolve(DenseMatrix& A, double* X, double TOL)
  Array<int> ipiv(N);
  LUFactors lu(A.Data(), ipiv);
  - if (!lu.Factor(N)) { return false; } // singular
  + if (!lu.Factor(N,TOL)) { return false; } // singular
  lu.Solve(N, 1, X);
  }
  