about the 3D dynamic analysis

[baozai]

hello. I want to know that when I do a dynamic analysis of a 3D dimensional frame, how many dofs of mass should I make？take node 1 as an example.
if I use the command as follow: mass 1 100 0 100 0. 0. 0.;
when I calculate the eigen of the structure, if the number of the eigen is 3, it can be done, but if the number is 5 the error is:

ArpackSolver::Error with _saupd info = -9999
Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 9factorization. The user is advised to check thatenough workspace and array storage has been allocated.
WARNING DirectIntegrationAnalysis::eigen() - EigenSOE failed in solve()
ArpackSolver::Error with _saupd info = -9999
Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 9factorization. The user is advised to check thatenough workspace and array storage has been allocated.
WARNING DirectIntegrationAnalysis::eigen() - EigenSOE failed in solve()

but if i use the command as mass 1 100 100 100 0. 0. 0.;
when I calculate the eigen of the structure, the eigen 5 could also be done. so I just want to know how to consider the mass command?

Thank you.

[baozai]

Will anybody help me about it?

[khunglongkhelua]

I also encounter the same problem like this


ArpackSolver::Error with _saupd info = -9999
Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 9factorization. The user is advised to check thatenough workspace and array storage has been allocated.

Can anyone explain what this warning means.

[fmk]

the arpack solver has problems sometimes if there is duplicate eigenvalues .. it also can only solve for m-1 eigenvalues, where m is the number of eigenvalues in the system.

[anuragraj]

I am encountering same problem...i have used the command mass 9 1 0 1 0 1 0...how should I tackle this error..??...