Title
Estimates in quadratic formulas
Abstract
LetA be a real symmetric positive definite matrix. We consider three particular questions, namely estimates for the error in linear systemsAx=b, minimizing quadratic functional minx(xTAx−2bTx) subject to the constraint ‖x‖=α, αA−1b‖, and estimates for the entries of the matrix inverseA−1. All of these questions can be formulated as a problem of finding an estimate or an upper and lower bound onuTF(A)u, whereF(A)=A−1 resp.F(A)=A−2,u is a real vector. This problem can be considered in terms of estimates in the Gauss-type quadrature formulas which can be effectively computed exploiting the underlying Lanczos process. Using this approach, we first recall the exact arithmetic solution of the questions formulated above and then analyze the effect of rounding errors in the quadrature calculations. It is proved that the basic relation between the accuracy of Gauss quadrature forf(λ)=λ−1 and the rate of convergence of the corresponding conjugate gradient process holds true even for finite precision computation. This allows us to explain experimental results observed in quadrature calculations and in physical chemistry and solid state physics computations which are based on continued fraction recurrences.
Year
DOI
Venue
1994
10.1007/BF02142693
Numerical Algorithms
Keywords
Field
DocType
Solid State,Conjugate Gradient,Continue Fraction,Quadratic Formula,Real Vector
Gauss–Kronrod quadrature formula,Mathematical optimization,Mathematical analysis,Positive-definite matrix,Tanh-sinh quadrature,Clenshaw–Curtis quadrature,Rate of convergence,Quadrature (mathematics),Quadratic formula,Gaussian quadrature,Mathematics
Journal
Volume
Issue
Citations 
8
2
25
PageRank 
References 
Authors
7.12
2
2
Name
Order
Citations
PageRank
Gene H. Golub12558856.07
Zdeněk Strakoš25410.51