• SJSU Singular Matrix Database
• Matrix group: Pothen

• Matrix: Pothen/skirt
• Description: skirt, with coordinates. From NASA, collected by Alex Pothen
• download as a MATLAB mat-file, file size: 335 KB. Use SJget(394) or SJget('Pothen/skirt') in MATLAB.

A singular value of A is guaranteed1 to be in the interval pictured by the blue bars around each of the calculated singular values.

Routine svds_err, version 1.0, used with Matlab 7.6.0.324 (R2008a) to calculate the 6 largest singular values and associated error bounds.
Routine spnrank, version 1.0, used with Matlab 7.6.0.324 (R2008a) to calculate singular values 9829 to 9834 and associated error bounds.

 Matrix properties (click for a legend) number of rows 12,598 number of columns 12,598 structural full rank? yes structural rank 12,598 numerical rank 9,831 dimension of the numerical null space 2,767 numerical rank / min(size(A)) 0.78036 Euclidean norm of A 23.314 calculated singular value # 9831 4.6429e-005 numerical rank defined using a tolerance max(size(A))*eps(norm(A)) = 4.4757e-011 calculated singular value # 9832 2.1958e-014 gap in the singular values at the numerical rank: singular value # 9831 / singular value # 9832 2.1144e+009 calculated condition number -2 condest Inf nonzeros 196,520 # of blocks from dmperm 7 # strongly connected comp. 7 entries not in dmperm blocks 0 explicit zero entries 0 nonzero pattern symmetry symmetric numeric value symmetry symmetric type binary structure symmetric Cholesky candidate? yes positive definite? no

 author NASA editor G. Kumfert, A. Pothen date 2003 kind structural problem 2D/3D problem? yes SJid 394 UFid 882

 Additional fields size and type coord full 12598-by-3

 Ordering statistics: AMD METIS DMPERM+ nnz(chol(P*(A+A'+s*I)*P')) 480,579 484,160 473,042 Cholesky flop count 3.4e+007 3.1e+007 3.0e+007 nnz(L+U), no partial pivoting 948,560 955,722 933,486 nnz(V) for QR, upper bound nnz(L) for LU 826,916 671,752 706,950 nnz(R) for QR, upper bound nnz(U) for LU 1,528,684 1,259,102 1,258,677

Maintained by Leslie Foster, last updated 24-Apr-2009.

Entries 5 through 14 in the table of matrix properties and the singular
value plot were created using SJsingular code. The other plots
and statistics are produced using utilities from the SuiteSparse package.
Matrix color plot pictures by cspy, a MATLAB function in the CSparse package.