• SJSU Singular Matrix Database
• Matrix group: Hohn
• Click here for a description of the Hohn group.
• Click here for a list of all matrices
• Click here for a list of all matrix groups

• Matrix: Hohn/fd18
• Description: M. Hohn, Univ Utah. Single-material crack problem, finite diff log grid
• download as a MATLAB mat-file, file size: 174 KB. Use SJget(396) or SJget('Hohn/fd18') in MATLAB.
• download in Matrix Market format, file size: 299 KB.
• download in Rutherford/Boeing format, file size: 238 KB.

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 16354 to 16359 and associated error bounds.  Matrix properties (click for a legend) number of rows 16,428 number of columns 16,428 structural full rank? yes structural rank 16,428 numerical rank 16,356 dimension of the numerical null space 72 numerical rank / min(size(A)) 0.99562 Euclidean norm of A 7.2893e+008 calculated singular value # 16356 0.0020102 numerical rank defined using a tolerance max(size(A))*eps(norm(A)) = 0.0019584 calculated singular value # 16357 0.0019096 gap in the singular values at the numerical rank: singular value # 16356 / singular value # 16357 1.0527 calculated condition number -2 condest 1.2361e+014 nonzeros 63,406 # of blocks from dmperm 1,061 # strongly connected comp. 1 entries not in dmperm blocks 1,859 explicit zero entries 0 nonzero pattern symmetry 0% numeric value symmetry 0% type real structure unsymmetric Cholesky candidate? no positive definite? no

 author M. Hohn editor T. Davis date 2003 kind materials problem 2D/3D problem? yes SJid 396 UFid 919

 Additional fields size and type b full 16428-by-1

 Ordering statistics: AMD METIS DMPERM+ nnz(chol(P*(A+A'+s*I)*P')) 8,300,663 13,612,979 648,420 Cholesky flop count 1.5e+010 2.9e+010 7.1e+007 nnz(L+U), no partial pivoting 16,584,898 27,209,530 1,282,271 nnz(V) for QR, upper bound nnz(L) for LU 766,230 617,644 632,463 nnz(R) for QR, upper bound nnz(U) for LU 1,452,963 1,270,956 1,235,890

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.