# Recent content by kalleC

1. ### Construction of minimum norm solution matrix

Homework Statement Consider the linear system of equations Ax = b b is in the range of A Given the SVD of a random matrix A; construct a full rank matrix B for which the solution: x = B^-1*b is the minimum norm solution. Also A is rank deficient by a known value and diagonalizable...
2. ### Condition number of a matrix

Homework Statement For a system of equations Ax = b Let dA be a random perturbation of the matrix A The error in Which dA fullfills the equality norm(A^-1 (da) x) = norm(A^-1) norm(dA) norm(x) (The SVD of A is known) (b is a known vector) Homework Equations The Attempt...
3. ### Effect of orthonormal projection on rank

Thank you very much =)
4. ### Effect of orthonormal projection on rank

They are equal? As the only way Q(S) would be dissimilar would be if rank(Q)<rank(R). But does not the reason for this have anything to do with Q being orthnormal? Otherwise couldn't Q act on R and cause some of the image to overlap effectively reducing the rank?
5. ### Effect of orthonormal projection on rank

Homework Statement Given rank(R) and a QR factorization A = QR, what is the rank(A) Homework Equations The Attempt at a Solution I want to know if multiplication by a full rank orthonormal matrix Q and an upper trapezoidal matrix R yields rank(R)=rank(Q*R)=rank(A) This is...
6. ### Oblique projector

p = [U 0] [U V]^-1 According to "Generalized inverses: theory and applications" by AvAdi Ben-Israel, Thomas Nall Eden Greville 0 is nullspace And sure as hell it works =D
7. ### Orthogonal projectors (minimization and variational problem)

Wow, I didn't know maths could be fun :P thanks a lot.
8. ### Oblique projector

Homework Statement Find the oblique projector P so where range(P) = range(U) and range(I-P) = range(W) Homework Equations P^2-P = 0 range(I-P) = null(P) The Attempt at a Solution It seems that U and W are complementary subspaces. According to...
9. ### Orthogonal projectors (minimization and variational problem)

Homework Statement S1 is in subspace of C^n. P unique orthogonal projector P : C^n -> S1, and x is in range of C^n. Show that the minimization problem: y in range of S1 so that: 2norm(x-y) = min 2norm(x-z) where z in range of S1 and variational problem: y in range of S1 so that...
10. ### Solution to system of linear equations in range of system matrix

Much appreciated!
11. ### Solution to system of linear equations in range of system matrix

Homework Statement See image. a) and b) have been solved. The problem is c) Homework Equations The Attempt at a Solution I really have no idea where to begin. For the three systems given there are solutions x in range(A) for system 1 and 2 but not for 3. Therefore I have been...