This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Homework 5 Math 471, Fall 2007 Assigned: Friday, October 5, 2007 Due: Friday, October 12, 2007 • Include a cover page • Clearly label all plots using title , xlabel , ylabel , legend • Use the subplot command to compare multiple plots • Include printouts of all Matlab code, labeled with your name, date, section, etc. (1) (Pivoting) (a) Prove that the matrix 0 1 1 1 does not have an LU decomposition. Use direct decomposition. Suppose that 0 1 1 1 = 1 ‘ 21 1 u 11 u 12 u 22 = u 11 u 12 ‘ 21 u 11 ‘ 21 u 12 + u 22 . Then u 11 = 0. But this implies 1 = ‘ 21 u 11 = 0. (b) Does the system 0 1 1 1 x y = a b have a unique solution for all a,b ∈ R ? (Why?) Yes. det 0 1 1 1 = 1 . (c) How can you modify the system in part (b) so that LU decomposition applies? Switch the two rows. 1 2 (2) (Gaussian Elimination with Partial Pivoting) Do page 169, # 7(a) by hand. r = 1 2 3 2 3 1 4 4 1 4 9 3 4 6 r = 2 1 3 5 / 2 1 17 / 2 4 1 4 9...
View
Full Document
 Winter '08
 LinZhi
 Math, Linear Algebra, Numerical Analysis

Click to edit the document details