Question: A matrix A is said to have band width k if all entries that are more than k slots away from the main diagonal are

A matrix A is said to have band width k if all entries that are more than k slots away from the main diagonal are zero: aij = 0 whenever |i - j| > k.
(a) Show that a tridiagonal matrix has band width1.
(b) Write down an example of a 6 × 6 matrix of band width 2 and one of band width 3.
(c) Prove that the L and U factors of a regular banded matrix have the same band width.
(d) Find the LU factorization of the matrices you wrote down in part (b).
(e) Use the factorization to solve the system Ax = b, where b is the column vector with all entries equal to 1.
(f) How many arithmetic operations are needed to solve Ax = b if A is banded?
(g) Prove or give a counterexample: the inverse of a banded matrix is banded.

Step by Step Solution

3.26 Rating (161 Votes )

There are 3 Steps involved in it

1 Expert Approved Answer
Step: 1 Unlock

a If matrix A is tridiagonal then the only nonzero elements in i th row are a ii1 a ii a ii1 So a ij ... View full answer

blur-text-image
Question Has Been Solved by an Expert!

Get step-by-step solutions from verified subject matter experts

Step: 2 Unlock
Step: 3 Unlock

Document Format (1 attachment)

Word file Icon

952-M-L-A-E (1729).docx

120 KBs Word File

Students Have Also Explored These Related Linear Algebra Questions!