[Scilab-users] eigs calculation

[Carrico, Paul]

Dear All,

I'm performing a (mechanical) calculation using the eigs and I've been noticing that the results are strongly sensitive on the unit system I'm using; I can understand that high numbers can lead to some numerical "issues" ...

Is there a way to increase the accuracy ?

Paul

PS: the 2 types of results


NB:
1 (MPa) = 1E6 (Pa)
1 (mm) = 1E-3 (m)
1 (Kg/m^3) = 1E12 (T/mm^3)

[u,v] = eigs(K((ddl_elem+1):$,(ddl_elem+1):$),M((ddl_elem+1):$,(ddl_elem+1):$),n,"SM");



a) calculation 1 in Pa, m, Kg/m^3
Natural frequency calculation:
                - Resonance 1 : 497.956 Hz
                - Resonance 2 : 3120.64 Hz
                - Resonance 3 : 5277.8 Hz
                - Resonance 4 : 6948.69 Hz
                - Resonance 5 : 8737.88 Hz
                - Resonance 6 : 15832.1 Hz
                - Resonance 7 : 17122.8 Hz
                - Resonance 8 : 20847.8 Hz
                - Resonance 9 : 26382.5 Hz
                - Resonance 10 : 28305.1 Hz
                - Resonance 11 : 34752 Hz
                - Resonance 12 : 36926.4 Hz
b) Calculation in MPa, mm, T/mm^3 ....
Natural frequency calculation:
                - Resonance 1 : 497.955 Hz
                - Resonance 2 : 497.956 Hz
                - Resonance 3 : 3120.59 Hz
                - Resonance 4 : 3120.64 Hz
                - Resonance 5 : 6948.69 Hz
                - Resonance 6 : 7463.93 Hz
                - Resonance 7 : 8737.56 Hz
                - Resonance 8 : 8737.88 Hz
                - Resonance 9 : 17121.6 Hz
                - Resonance 10 : 17122.8 Hz
                - Resonance 11 : 20847.8 Hz
                - Resonance 12 : 22390 Hz

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