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control_eigen index type_of_eigen_analysis number_of_modes

With this option you can ask for eigenvalues (and eigenvectors). The eigenvectors are determined for the principal unknowns in the system (like velocity, temperature, etc.). With type_of_eigen_analysis you can determine which eigen problem will be solved. This option is only available after the matrices have been set up with -matrix_direct or -matrix_iterative in control_solver. And it is assumed that the matrices used in the eigenmodes determination are symmetric.

If type_of_eigen_analysis is set to -matrix, the eigen modes of the matrix which is used for iteration will be solved.

If type_of_eigen_analysis is set to -buckling, the buckling modes of the system will be solved. This option is still experimental and being tested. The eigenvalues tell how much times the load applied to the system at the time of buckling mode determination can be applied before buckling is to be expected.

The eigenvalues are put in the control_eigen_values record. The eigenvectors are put in the node_eigen records.

Warning: the eigensolvers we use are not tuned for finite element analysis. So the eigensolvers may be very slow, and large amounts of memory may be consumed.

Warning: the -buckling is still experimental and being tested.

See also control_eigen_scale.


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Next: control_eigen_scale index largest_component Up: Input: data part Previous: control_data_put_integer index ...   Contents
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1998-11-16