## BLCKHOLE: BCS Structural Engineering Matrices (linear equations)Geodesic dome clamped to rectangular base

### from set BCSSTRUC6, from the Harwell-Boeing Collection

An artificial finite-element model consisting of a finely gridded geodesic dome clamped to a coarsely gridded rectangular base. Because of the difference in gridding factors, the interface nodes on the base have a very high order. The strange gridding plays havoc with orderings based on level structures, and is nearly a worst case for the Gibbs-Poole-Stockmeyer heuristic. Reverse Cuthill-McKee and Gibbs-Poole- Stockmeyer are nearly a factor of two away from obtaining the minimum bandwidth of this problem. General sparse methods fair well despite the strange gridding.

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## Visualizations

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## Matrix Statistics

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Size Type
2132 x 2132, 8502 entries pattern symmetric indefinite
Nonzeros
totaldiagonalbelow diagonalabove diagonalA-A'
14872 2132 6370 6370 0
Column Data Row Data
Average nonzeros per column : 7
Standard deviation : 0.95

index nonzeros 2073 20 2074 1

Average nonzeros per row : 7
Standard deviation : 0.95

index nonzeros 2073 20 2074 1

Bandwidths Profile Storage
 lower upper 1806 1806 55 170
minmaxave.std.dev.
lower bandwidth1 1806 89 2.1e+02
upper bandwidth1 1806 89 2.1e+02

Symmetric skyline storage requirement:190620

Heaviest diagonals
 offset from main nonzeros accumulated percent 0 -1 1 -18 18 -17 17 -16 16 -15 2132 1917 1917 350 350 330 330 310 310 290 14.34 27.23 40.12 42.47 44.82 47.04 49.26 51.34 53.43 55.38

Top 10 out of 699 nonvoid diagonals.
Conditioning
Pattern matrix. No conditioning information.

## Set Information

Set BCSSTRUC6
Source: Ed Meyer, Boeing Computer Services
Discipline:Structural engineering
Accession:Summer 1983

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