• SJSU Singular Matrix Database
• Matrix group: HB

• Matrix: HB/curtis54
• Description: UNSYMMETRIC PATTERN OF CURTIS, 1971
• download as a MATLAB mat-file, file size: 1 KB. Use SJget(89) or SJget('HB/curtis54') in MATLAB.

Routine svd from Matlab 7.6.0.324 (R2008a) used to calculate the singular values.

 Matrix properties (click for a legend) number of rows 54 number of columns 54 structural full rank? yes structural rank 54 numerical rank 50 dimension of the numerical null space 4 numerical rank / min(size(A)) 0.92593 Euclidean norm of A 6.7242 calculated singular value # 50 0.044184 numerical rank defined using a tolerance max(size(A))*eps(norm(A)) = 4.7962e-014 calculated singular value # 51 9.6733e-016 gap in the singular values at the numerical rank: singular value # 50 / singular value # 51 4.5676e+013 calculated condition number 9.5304e+016 condest Inf nonzeros 291 # of blocks from dmperm 1 # strongly connected comp. 1 entries not in dmperm blocks 0 explicit zero entries 0 nonzero pattern symmetry 95% numeric value symmetry 95% type binary structure unsymmetric Cholesky candidate? no positive definite? no

 author A. Curtis editor A. Curtis, I. Duff, J. Reid date 1971 kind 2D/3D problem 2D/3D problem? yes SJid 89 UFid 109

 Ordering statistics: AMD METIS nnz(chol(P*(A+A'+s*I)*P')) 224 239 Cholesky flop count 9.8e+002 1.2e+003 nnz(L+U), no partial pivoting 394 424 nnz(V) for QR, upper bound nnz(L) for LU 266 304 nnz(R) for QR, upper bound nnz(U) for LU 556 565

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.