*HEADING
: EIGENVALUE ANALYSIS OF AN UNCONSTRAINED 1-ELEMENT MESH  [M3D4R]
*PREPRINT,ECHO=YES,HISTORY=NO,MODEL=NO
*NODE,NSET=NALL
 1,0.,0.
 3,7.,0.
 7,0.,7.
 9,7.,7.
*ELEMENT,TYPE=M3D4R, ELSET=EALL
 1,1,3,9,7
*MEMBRANE SECTION,MATERIAL=A1, ELSET=EALL
 0.1, 
*MATERIAL,NAME=A1
*ELASTIC
 3.E6,.3
*DENSITY
7.5E-4, 
*STEP
*FREQUENCY, eigensolver=lanczos
9, , ,-1.E7 
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP