Def:Projection
Def:InnerProductSpace
Def:OrthSubspace
Def:OrthProjection
Def:BestApprox
Def:QRFactorization
Thm:QRFactorization
Thm:QRFactorizationGSAlgo
Def:HHMat
Def:FullQR
Def:LeastSquaresSol
Def:NormalEquation
Thm:UniquenessLS
Def:GenLinModel
Def:LineOfReg
Def:MultipleRegression