zero length element

[hnsmengyu]

If the zero length element is used in the SDOF analysis, how can I get the eigen values by the eigen command,my programme is below:
wipe
model basic -ndm 2 -ndf 3
...
node 1 0.0 0.0
node 2 0.0 0.0
fix 1 1 1 1
mass 2 $M 1.0E-8 0.0

set matTag 1
set Fy [expr 147.058*$kip]
set b 0.22
uniaxialMaterial Steel01 $matTag $Fy $K $b
element zeroLength 1 1 2 -mat $matTag -dir 1
mistakes may exist in it, because it can't output eigen info. But I don't know why!
Anyone can help me !
Thank you!

[vesna]

To get eigen values use this command:

eigen -fullGenLapack 1

where 1 is number of modes.

However the eigenvalue will be zero in your case since the only element you have is a zero-length element.