Direct Minimization of the least-squares spectral element functional - Part I: Direct solver

  • Authors:

  • Wijnand Hoitinga;Roel de Groot;Marcel Kwakkel;Marc Gerritsma

  • Affiliations:

  • Department of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, The Netherlands;TNO Institute of Applied Physics, Flow and Structural Dynamics, P.O. Box 155, 2600 AD Delft, The Netherlands;Department of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, The Netherlands;Department of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, The Netherlands

  • Venue:
  • Journal of Computational Physics
  • Year:
  • 2008

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Abstract

This paper describes an equivalent but improved least-squares formulation for the numerical approximation of the solution of partial differential equations. Instead of using variational analysis to impose the conditions for minimizing the residual, the residuals are minimized directly, thus leading to a method we will denote by Direct Minimization (DM). DM circumvents setting up the normal equations which consists of matrix-matrix multiplications. Matrix-matrix multiplications are expensive, may lead to loss of accuracy and destroy the sparsity pattern present in the original system. The condition number of the DM formulation is the square root of the condition number which would be obtained if variational analysis was employed. An element-by-element procedure will be presented which allows for parallelization of DM. A computational comparison between DM and the conventional least-squares formulation based on variational analysis will be presented.