Matrix: Boeing/nasa1824
Description: STRUCTURE FROM NASA LANGLEY, 1824 DEGREES OF FREEDOM
(undirected graph drawing) |
Matrix properties | |
number of rows | 1,824 |
number of columns | 1,824 |
nonzeros | 39,208 |
structural full rank? | yes |
structural rank | 1,824 |
# of blocks from dmperm | 1 |
# strongly connected comp. | 1 |
explicit zero entries | 0 |
nonzero pattern symmetry | symmetric |
numeric value symmetry | symmetric |
type | real |
structure | symmetric |
Cholesky candidate? | yes |
positive definite? | no |
author | R. Grimes |
editor | T. Davis |
date | 1995 |
kind | duplicate structural problem |
2D/3D problem? | yes |
Additional fields | size and type |
b | full 1824-by-1 |
Notes:
Let A1=Nasa/nasa1824 and A2=Boeing/nasa1824. A1 and A2 have the same nonzero pattern. A1 and A2 differ in value in only 386 entries out of 39208, and only in 21 columns of the lower triangular part; tril(A(196:321,196:216)) and the same rows of the upper triangular part. The magnitudes of the entries in A2 in this region of the matrix are all tiny, and have only 9 digits if printed in base-10 (unlike the other entries, which have full precision). I suspect A2 (Boeing/nasa1824) is a corrupted version of A1 (Nasa/nasa1824).
Ordering statistics: | result |
nnz(chol(P*(A+A'+s*I)*P')) with AMD | 69,309 |
Cholesky flop count | 4.6e+06 |
nnz(L+U), no partial pivoting, with AMD | 136,794 |
nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD | 157,808 |
nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD | 289,058 |
SVD-based statistics: | |
norm(A) | 2.12172e+07 |
min(svd(A)) | 3.60113 |
cond(A) | 5.8918e+06 |
rank(A) | 1,824 |
sprank(A)-rank(A) | 0 |
null space dimension | 0 |
full numerical rank? | yes |
singular values (MAT file): | click here |
SVD method used: | s = svd (full (A)) ; |
status: | ok |
For a description of the statistics displayed above, click here.
Maintained by Tim Davis, last updated 12-Mar-2014.
Matrix pictures by cspy, a MATLAB function in the CSparse package.
Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.