## Group ANSYS

Group Description |
Underdetermined systems needing well-conditioned bases to be found. The goal is to find a permutation or factorization that places A in upper trapezoidal form, [R1 R2] where R1 is well-conditioned, square, and upper triangular, and where R1\R2 is as sparse as possible. Submitted to the UF collection by Emmannuel Delor, ANSYS. opts.tol = 0.01 ; [m n] = size(A) ; x = ones (n,1) ; y = A*x ; [c R P info] = spqr (A, y, opts) ; info Rs = R (:, 1:m) ; % must be well conditioned fprintf ('condest(Rs) %g\n', condest (Rs)) ; xs = x (1:m) ; xm = x (m+1:n) ; A2 = -Rs \ R (:, m+1:n) ; y2 = Rs \ c ; norm(A2*xm + y2 - xs) % should be very small nnz (A2) % should also be as small as possible |
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Displaying

**all 3**collection matricesId | Name | Group | Rows | Cols | Nonzeros | Kind | Date | Download File |
---|---|---|---|---|---|---|---|---|

2651 | Delor64K | ANSYS | 64,719 | 1,785,345 | 652,140 | Least Squares Problem | 2011 | MATLAB Rutherford Boeing Matrix Market |

2652 | Delor295K | ANSYS | 295,734 | 1,823,928 | 2,401,323 | Least Squares Problem | 2011 | MATLAB Rutherford Boeing Matrix Market |

2653 | Delor338K | ANSYS | 343,236 | 887,058 | 4,211,599 | Least Squares Problem | 2011 | MATLAB Rutherford Boeing Matrix Market |