Zobrazeno 1 - 10
of 124
pro vyhledávání: '"Forsgren, Anders"'
Quasi-Newton methods form an important class of methods for solving nonlinear optimization problems. In such methods, first order information is used to approximate the second derivative. The aim is to mimic the fast convergence that can be guarantee
Externí odkaz:
http://arxiv.org/abs/2407.03072
Delineating and planning with respect to regions suspected to contain microscopic tumor cells is an inherently uncertain task in radiotherapy. The recently proposed \textit{clinical target distribution} (CTD) is an alternative to the conventional \te
Externí odkaz:
http://arxiv.org/abs/2210.06049
We investigate quasi-Newton methods for minimizing a strictly convex quadratic function which is subject to errors in the evaluation of the gradients. The methods all give identical behavior in exact arithmetic, generating minimizers of Krylov subspa
Externí odkaz:
http://arxiv.org/abs/2109.00072
Autor:
Ek, David, Forsgren, Anders
We give a derivation of the method of conjugate gradients based on the requirement that each iterate minimizes a strictly convex quadratic on the space spanned by the previously observed gradients. Rather than verifying that the search direction has
Externí odkaz:
http://arxiv.org/abs/2011.02337
Publikováno v:
Silva Fennica, Vol 32, Iss 3 (1998)
To improve our understanding of factors influencing the success of natural regeneration with downy birch (Betula pubescens Ehrh.) and silver birch (Betula pendula Roth) on abandoned farmlands, a survey was conducted to analyse the effects of site con
Externí odkaz:
https://doaj.org/article/e8f0e31abbd94b5cb6ca2d11e65b62d4
Autor:
Ek, David, Forsgren, Anders
Publikováno v:
Comput. Optim. Appl. 86, 1-48 (2023)
The focus in this work is on interior-point methods for inequality-constrained quadratic programs, and particularly on the system of nonlinear equations to be solved for each value of the barrier parameter. Newton iterations give high quality solutio
Externí odkaz:
http://arxiv.org/abs/2009.07913
Autor:
Ek, David, Forsgren, Anders
Publikováno v:
Comput. Optim. Appl. 79, 155-191 (2021)
The focus in this paper is interior-point methods for bound-constrained nonlinear optimization, where the system of nonlinear equations that arise are solved with Newton's method. There is a trade-off between solving Newton systems directly, which gi
Externí odkaz:
http://arxiv.org/abs/2004.04057
Autor:
Forsgren, Anders, Wang, Fei
Pivoting methods are of vital importance for linear programming, the simplex method being the by far most well-known. In this paper, a primal-dual pair of linear programs in canonical form is considered. We show that there exists a sequence of pivots
Externí odkaz:
http://arxiv.org/abs/1908.09735
Publikováno v:
Biomedical Physics & Engineering Express 2019
Interfractional geometric uncertainties can lead to deviations of the actual delivered dose from the prescribed dose distribution. To better handle these uncertainties during treatment, the authors propose a dynamic framework for robust adaptive radi
Externí odkaz:
http://arxiv.org/abs/1811.00391
Autor:
Engberg, Lovisa, Forsgren, Anders
The purpose of this study is to give an exact formulation of optimization of volumetric-modulated arc therapy (VMAT) with sliding-window delivery, and to investigate the plan quality effects of decreasing the number of sliding-window sweeps made on t
Externí odkaz:
http://arxiv.org/abs/1810.08610