problem description
title="Modal Analysis of Spring Mass"
nodes=3 elements=2 analysis=modal

analysis parameters
mass-mode=lumped

nodes
1	x=0.0	y=0.0	constraint=fixed
2	x=1.0		constraint=free		mass=10
3	x=2.0		constraint=free		mass=10

truss elements
1	nodes=[1,2]	material=steel
2	nodes=[2,3]	material=steel

material properties
steel	A=1.0	E=1000   rho=0.0	Rk=0.002

constraints
fixed	Tx=c Ty=c Tz=c
free	Tx=u Ty=c Tz=c

end