creates a general purpose solver . use this if you are not sure what you need . concode_field_sep PlaceHolder placeHolder concode_field_sep LinearSolver<DenseMatrix64F> leastSquares concode_elem_sep LinearSolver<DenseMatrix64F> pseudoInverse concode_elem_sep LinearSolver<DenseMatrix64F> linear concode_elem_sep LinearSolver<DenseMatrix64F> symmPosDef concode_elem_sep AdjustableLinearSolver adjustable concode_elem_sep LinearSolver<DenseMatrix64F> leastSquaresQrPivot