document the change

Author: yixuan

AUTHORS.md

@@ -2,15 +2,17 @@ The files
 
 - `include/Spectra/LinAlg/TridiagEigen.h`
 - `include/Spectra/LinAlg/UpperHessenbergEigen.h`
+- `include/Spectra/LinAlg/UpperHessenbergSchur.h`
 
 were adapted from
 
 - `Eigen/src/Eigenvaleus/SelfAdjointEigenSolver.h`
 - `Eigen/src/Eigenvaleus/EigenSolver.h`
+- `Eigen/src/Eigenvaleus/RealSchur.h`
 
 in the [Eigen](http://eigen.tuxfamily.org/) library.
 
-The authors for these two files were Gael Guennebaud <[email protected]>
+The authors for these three files were Gael Guennebaud <[email protected]>
 and Jitse Niesen <[email protected]>.
 
 The file `include/contrib/LOBPCGSolver.h` was originally contributed by Anna Araslanova.

CHANGELOG.md

@@ -6,6 +6,8 @@
 - Added the `SymGEigsShiftSolver` class for symmetric generalized eigen solver with real shifts
 - Added the wrapper class `SymShiftInvert` that can be used with `SymGEigsShiftSolver`
 - Added test code for symmetric generalized eigen solver with real shifts
+- Added an internal class `UpperHessenbergSchur` to compute the Schur decomposition of
+  upper Hessenberg matrices more efficiently
 - Added a `Flags` template parameter to every matrix operation class
   (e.g. `DenseCholesky` and `DenseSymMatProd`), whose possible values are `Eigen::ColMajor`
   and `Eigen::RowMajor`. This parameter allows these wrapper classes to handle row-major matrices.