An Augmented Conjugate Gradient Method for Solving Consecutive Symmetric Positive Definite Linear Systems

  • Authors:
  • Jocelyne Erhel;Frédéric Guyomarc'h

  • Affiliations:
  • -;-

  • Venue:
  • SIAM Journal on Matrix Analysis and Applications
  • Year:
  • 2000

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Abstract

Many scientific applications require one to solve successively linear systems Ax=b with different right-hand sides $b$ and a symmetric positive definite matrix A. The conjugate gradient method applied to the first system generates a Krylov subspace which can be efficiently recycled thanks to orthogonal projections in subsequent systems. A modified conjugate gradient method is then applied with a specific initial guess and initial descent direction and a modified descent direction during the iterations. This paper gives new theoretical results for this method and proposes a new version. Numerical experiments show the efficacy of our method even for quite different right-hand sides.