about eigen command

hanjun009 · Post by **hanjun009** » Tue Oct 21, 2008 6:59 am

dear silvia:
i use "eigen 6" command to get the eigenvalues of three-floor frame. one floor have 3dofs due to rigidDiaphragm assumption. But the solve don't work, the error is:
"BandArpackSolver::Error with _saupd info = -9999
Could not build an Arnoldi factorization.IPARAM(5) returns the size of the current Arnoldi factorization. The user is advised to check thatenough workspace and array storage has been allocated. Warning FrequencyAlgo::solveCurrentStep() - the EigenSOE failed in solve().
EigenAnalysis::analyze() - algorithm failed eigen values for mode analysis:
"

i also try the example 5 of the opensees example manual. but the same error happen.
i try one floor frame with 3 dofs. but the "eigen 3" don't work also.
why?

thank you very much

silvia · Post by **silvia** » Tue Oct 21, 2008 7:33 am

the eigen solver is limited to Ndof-1 modes.

hanjun009 · Post by **hanjun009** » Tue Oct 21, 2008 7:12 pm

dear silvia:
thank you for your reply! but the example 5 have 9 dof. the eigen solver should give 8 modes. but it give 4 modes only. why?

thank you again

silvia · Post by **silvia** » Wed Oct 22, 2008 5:04 am

how many inertial/dynamic dofs does it have?

hanjun009 · Post by **hanjun009** » Thu Oct 23, 2008 3:03 am

'example 5-Three-Dimensional Rigid Frame' in the opensees example manual have 9 dynamic dofs(every floor have 3 dofs).

silvia · Post by **silvia** » Thu Oct 23, 2008 9:29 am

please refer to the current examples manual:

http://opensees.berkeley.edu/OpenSees/m ... nual/HTML/

hanjun009 · Post by **hanjun009** » Thu Oct 23, 2008 10:32 pm

i am just download from the current examples manual: http://opensees.berkeley.edu/OpenSees/m ... nual/HTML/
the exmple 5 is located in the section 'the Original Examples Primer' of the manual.

silvia · Post by **silvia** » Fri Oct 24, 2008 5:27 am

right, please use the current examples -- i can't guarantee the accurateness of the old examples.