Regularization by truncated Cholesky factorization: A comparison of four different approaches

  • Authors:
  • Barbara Kaltenbacher

  • Affiliations:
  • University of Erlangen, Germany

  • Venue:
  • Journal of Complexity
  • Year:
  • 2007

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Abstract

Due to the principle of regularization by restricting the number of degrees of freedom, truncating the Cholesky factorization of a symmetric positive definite matrix can be expected to have a stabilizing effect. Based on this idea, we consider four different approaches for regularizing ill-posed linear operator equations. Convergence in the noise free case as well as-with an appropriate a priori truncation rule-in the situation of noisy data is analyzed. Moreover, we propose an a posteriori truncation rule and characterize its convergence. Numerical tests illustrate the theoretical results. Both analysis and computations suggest one of the four variants to be favorable to the others.