Compute Condition Number of Matrix A

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SUMMARY

The condition number of the matrix A, defined as K(A) = ||A|| * ||A^-1||, was computed incorrectly in the forum discussion. The matrix A is given as | 1 1 | | E -E |, and its infinity norm ||A|| is correctly calculated as 2. However, the inverse matrix A^-1 was incorrectly derived, leading to an inaccurate condition number of K(A) = 2(1-E). The correct approach emphasizes the importance of understanding matrix norms and the behavior of the condition number as E approaches zero, indicating significant instability.

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Homework Statement


Compute the condition number of the following matrix:

| 1 1 |
| E -E |

where E<<l infinity norm.


Homework Equations



l infinity norm: ||x||infinity = max |xi| where i goes from 1 to n.

Condition number: K(A) = ||A||*||A^-1||



The Attempt at a Solution


A=
| 1 1 |
| E -E |

A^-1=
| 1 -E |
| -1 -E |

||A||infinity = max(2,0) = 2
||A^-1||infinity = max(1-E,-1-E) = 1-E

K(A) = 2(1-E) = 2-2E

Is this right or am I completely off? Thanks!
 
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Your result for A^-1 is wrong.
Additionally, you gave the definition for the norm of a vector but explained nothing concerning the norm of matrix. You should also explain how you calculated the norm of A and A^-1.
The end result is wrong of course.
It should be clear that the condition number increases a lot when E goes to zero.
 

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