Search for dissertations about: "sparse approximate inverse"

Showing result 1 - 5 of 6 swedish dissertations containing the words sparse approximate inverse.

2. 1. Parallelization of dynamic algorithms for electronic structure calculations

   Author : Anton G. Artemov; Emanuel H. Rubensson; Maya Neytcheva; Bo Kågström; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; parallelization; task-based programming; matrix algorithms; sparse matrices; inverse factorization; localized computations; density matrix methods; electronic structure calculations; Scientific Computing; Beräkningsvetenskap;

   Abstract : The aim of electronic structure calculations is to simulate behavior of complex materials by resolving interactions between electrons and nuclei in atoms at the level of quantum mechanics. Progress in the field allows to reduce the computational complexity of the solution methods to linear so that the computational time scales proportionally to the size of the physical system. READ MORE

4. 2. Robust Preconditioners Based on the Finite Element Framework

   Author : Erik Bängtsson; Maya Neytcheva; Per Lötstedt; Svetozar Margenov; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; FEM; iterative solution method; algebraic multilevel preconditioner; sparse approximate inverse; block preconditioner; Schur complement approximation; nonsymmetric saddle point matrix; isostatic glacial adjustment; pre-stress advection; elasticity; viscoelasticity; in compressible solid; ABAQUS; BEM DDM; Scientific Computing; Beräkningsvetenskap;

   Abstract : Robust preconditioners on block-triangular and block-factorized form for three types of linear systems of two-by-two block form are studied in this thesis. The first type of linear systems, which are dense, arise from a boundary element type of discretization of crack propagation problems. READ MORE

5. 3. Fast Numerical Techniques for Electromagnetic Problems in Frequency Domain

   Author : Martin Nilsson; Per Lötstedt; Abderrahmane Bendali; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fast Multipole Method; Minimal Residual Interpolation; Sparse Approximate Inverse preconditioning; Method of Moments; fast solvers; iterative methods; multiple right-hand sides; error analysis; Numerical Analysis; Numerisk analys;

   Abstract : The Method of Moments is a numerical technique for solving electromagnetic problems with integral equations. The method discretizes a surface in three dimensions, which reduces the dimension of the problem with one. A drawback of the method is that it yields a dense system of linear equations. READ MORE

6. 4. Pontryagin approximations for optimal design

   Author : Jesper Carlsson; Anders Szepessy; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Topology Optimization; Inverse Problems; Hamilton-Jacobi; Regularization; Error Estimates; Impedance Tomography; Numerical analysis; Numerisk analys;

   Abstract : This thesis concerns the approximation of optimally controlled partial differential equations for applications in optimal design and reconstruction. Such optimal control problems are often ill-posed and need to be regularized to obtain good approximations. READ MORE

7. 5. Iterative solution of Maxwell's equations in frequency domain

   Author : Martin Nilsson; Per Lötstedt; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

   Abstract : We have developed an iterative solver for the Moment Method. It computes a matrix–vector product with the multilevel Fast Multipole Method, which makes the method scale with the number of unknowns. The iterative solver is of Block Quasi-Minimum Residual type and can handle several right-hand sides at once. READ MORE