諸分野のための数学研究会

過去の記録 ~08/06次回の予定今後の予定 08/07~

開催情報 火曜日 10:30~11:30 数理科学研究科棟(駒場) 056号室
担当者 儀我美一、石村直之(一橋大学)、齊藤宣一、山本昌宏
セミナーURL http://coe.math.sci.hokudai.ac.jp/sympo/various/
目的 北海道大学のHPには、第1回(2005年6月22日)~第22回(2009年2月18日)の情報が掲載されております。

2008年08月06日(水)

10:30-14:00   数理科学研究科棟(駒場) 056号室
伊東一文氏(10:30-11:30)
Yimin Wei氏(13:00-14:00)

Kazufumi Ito 氏 (North Carolina State University) 10:30-11:30
Adaptive Tikhonov Regularization for Inverse Problems
[ 講演概要 ]
Tikhonov regularization method plays a critical role in ill-posed inverse problems, arising in applications including computerized tomography, inverse scattering and image processing. The goodness of the inverse solution heavily depends on selection of the regularization parameter. Commonly used methods rely on a priori knowledge of the noise level. A method that automatically estimates the noise level and selects the regularization parameter automatically is presented.
Yimin Wei 氏 (Fudan University) 13:00-14:00
On mixed and componentwise condition numbers for Moore-Penrose inverse and linear least squares problems
[ 講演概要 ]
Classical condition numbers are normwise: they measure the size of both input perturbations and output errors using some norms. To take into account the relative of each data component, and a possible data sparseness, componentwise condition numbers have been increasingly considered. These are mostly of two kinds: mixed and componentwise. In this talk, we give explicit expressions, computable from the data, for the mixed and componentwise condition numbers for the computation of the Moore-Penrose inverse as well as for the computation of solutions and residues of linear least squares problems. In both cases the data matrices have full column (row) rank.