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BCSSTK02: BCS Structural Engineering Matrices (eigenvalue matrices)
Oil rig -- statically condensed

from set BCSSTRUC1, from the Harwell-Boeing Collection

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From generalized eigenvalue problem Kx=(lambda)Mx. This is matrix K; matrix M is BCSSTM02 from BCSSTRUC1 set.
Result of applying static condensation to the oil rig model represented by BCSSTK04 and BCSSTM04. Static condensation can be applied in cases where the mass matrix is singular to reduce the problem order while preserving the spectrum. However, the reduced stiffness matrix is usually dense, which is the case here. Good sparse eigenvalue codes should be able to solve a large sparse problem much more quickly than a dense code can solve the reduced problem of order one-half or one-third the original. This problem is probably too small to demonstrate that effect.

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Matrix Statistics

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Size Type
66 x 66, 2211 entries real symmetric positive definite
totaldiagonalbelow diagonalabove diagonalA-A'
4356 66 2145 2145 0
Column Data Row Data
Average nonzeros per column : 66
Standard deviation : 0

longest1 66
shortest1 66

Average nonzeros per row : 66
Standard deviation : 0

longest1 66
shortest1 66

Bandwidths Profile Storage
lower66 upper66
average |i-j|22
lower bandwidth1 66 34 19
upper bandwidth1 66 34 19

Symmetric skyline storage requirement:2211

Heaviest diagonals
offset from main0 -1 1 -2 2 -3 3 -4 4 -5
nonzeros66 65 65 64 64 63 63 62 62 61
accumulated percent 1.52 3.01 4.50 5.97 7.44 8.8810.3311.7513.1814.58

Top 10 out of 131 nonvoid diagonals.
Frobenius norm5.3e+04 condition number (est.)1.3e+04
2-norm (est.)1.8e+04 diagonal dominanceno

Set Information

Source: John Lewis, Boeing Computer Services, Seattle, Washington, USA
Discipline:Dynamic analyses in structural engineering
Accession:Summer 1982

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Last change in this page: Wed Sep 22 13:33:23 US/Eastern 2004 [Comments: ]