TY - RPRT TI - Modifications of the limited-memory BNS method for better satisfaction of previous quasi-Newton conditions AU - Vlček, Jan AB - Several modifications of the limited-memory variable metric BNS method for large scale un- constrained optimization are proposed, which consist in corrections (derived from the idea of conjugate directions) of the used difference vectors to improve satisfaction of previous quasi-Newton conditions, utilizing information from previous or subsequent iterations. In case of quadratic objective functions, conjugacy of all stored diffrence vectors and satisfaction of quasi-Newton conditions with these vectors is established. There are many possibilities how to realize this approach and although only two methods were implemented and tested, preliminary numerical results are promising. UR - http://hdl.handle.net/11104/0203700 UR - http://www.nusl.cz/ntk/nusl-80971 A2 - Lukšan, Ladislav LA - eng KW - variable metric methods KW - the BFGS update KW - unconstrained minimization KW - preliminary numerical results KW - limited-memory methods KW - conjugate directions UR - http://invenio.nusl.cz/record/80971/files/v1127-11.pdf UR - http://invenio.nusl.cz/record/80971/files/content.csg.pdf PY - 2011 PB - Ústav informatiky, Pod vodárenskou věží 2, 182 07 Praha 8, http://www.cs.cas.cz/ ER -