In: Advanced Math
For a 2 by 2 invertible matrix A, define the condition number to be cond(A) = ||A|| ⋅ ||A||-1. Assume that the matrix norm is defined using the Euclidean vector norm.
(a) Find two 2by2 invertible matrices B and C such that cond(B + C) < cond(B) + cond(C).
(b) Find two 2by2 invertible matrices B and C such that cond(B + C) > cond(B) + cond(C).
(c) Suppose that A is a symmetric invertible 2by2 matrix. Find cond(2A) and cond(A2) in terms of cond(A).
(d)do the results from part (c) hold if A is not symmetric? You can either prove the results, or find counterexamples.