The files
include/Spectra/LinAlg/TridiagEigen.hinclude/Spectra/LinAlg/UpperHessenbergEigen.hinclude/Spectra/LinAlg/UpperHessenbergSchur.h
were adapted from
Eigen/src/Eigenvaleus/SelfAdjointEigenSolver.hEigen/src/Eigenvaleus/EigenSolver.hEigen/src/Eigenvaleus/RealSchur.h
in the Eigen library.
The authors for these three files were Gael Guennebaud gael.guennebaud@inria.fr and Jitse Niesen jitse@maths.leeds.ac.uk.
The file include/contrib/LOBPCGSolver.h was originally contributed by Anna Araslanova.
The Jacobi-Davidson solvers were written by Felipe Zapata, Nicolas Renaud, Victor Azizi, Pablo Lopez-Tarifa and Jens Wehner from the Netherlands eScience Center J.Wehner@esciencecenter.nl.
The Catch library included for unit testing was written by Phil Nash github@philnash.me.
Other part of Spectra was written by Yixuan Qiu yixuan.qiu@cos.name.