decompositions: fix Eigen type

Author: jcarpent

include/eigenpy/decompositions/LDLT.hpp

@@ -54,7 +54,7 @@ namespace eigenpy
            "Returns the LDLT decomposition matrix.",
            bp::return_value_policy<bp::return_by_value>())
 
-      .def("rankUpdate",(Solver (Solver::*)(const VectorType &, const RealScalar &))&Solver::template rankUpdate<VectorType>,
+      .def("rankUpdate",(Solver (Solver::*)(const Eigen::MatrixBase<VectorType> &, const RealScalar &))&Solver::template rankUpdate<VectorType>,
            bp::args("self","vector","sigma"))
 
 #if EIGEN_VERSION_AT_LEAST(3,2,90)