@article {17677, title = {A note on generalized and hypergeneralized projectors}, journal = {Linear Algebra and its Applications}, volume = {412}, year = {2006}, month = {2006/01/15/}, pages = {408 - 411}, abstract = {Gro{\ss} and Trenkler [Generalized and hypergeneralized projectors, Linear Algebra Appl. 264 (1997) 463{\textendash}474] have introduced two generalizations of orthogonal projectors called generalized projectors and hypergeneralized projectors. In this note we characterize these generalizations by their spectral decompositions.}, keywords = {Generalized projection, projection, Spectral decomposition}, isbn = {0024-3795}, doi = {10.1016/j.laa.2005.07.022}, url = {http://www.sciencedirect.com/science/article/pii/S0024379505003836}, author = {Stewart, G.W.} }