*HEADING
: EIGENVALUE ANALYSIS OF AN UNCONSTRAINED 1-ELEMENT MESH  [STRI3]
*PREPRINT,ECHO=YES,HISTORY=NO,MODEL=NO
*NODE
1    , 0.        , 0.
2, 10.,0.
3, 0.,10.
*ELEMENT,TYPE=STRI3, ELSET=EALL
1, 1,2,3
*SHELL SECTION,MATERIAL=A1, ELSET=EALL
.1, 3
*MATERIAL,NAME=A1
*ELASTIC
3.E6      , 0.3
*DENSITY
7.5E-4, 
*STEP
*FREQUENCY, eigensolver=lanczos, SIM=NO
10, , ,-1.E7
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP