template<typename Derived>
class Eigen::SolverBase< Derived >
A base class for matrix decomposition and solvers.
 Template Parameters

Derived  the actual type of the decomposition/solver. 
Any matrix decomposition inheriting this base class provide the following API:
MatrixType A, b, x;
DecompositionType dec(A);
x = dec.solve(b);
x = dec.transpose().solve(b);
x = dec.adjoint().solve(b);
 Warning
 Currently, any other usage of transpose() and adjoint() are not supported and will produce compilation errors.
 See also
 class PartialPivLU, class FullPivLU, class HouseholderQR, class ColPivHouseholderQR, class FullPivHouseholderQR, class CompleteOrthogonalDecomposition, class LLT, class LDLT, class SVDBase