The choice of a suitable random matrix model of a complex system is very se
nsitive to the nature of its complexity. The statistical spectral analysis
of various complex systems requires, therefore, a thorough probing of a wid
e range of random matrix ensembles which is not an easy task. It is highly
desirable, if possible, to identify a common mathematical structure among a
ll the ensembles and analyze it to gain information about the ensemble prop
erties. Our successful search in this direction leads to the Calogero Hamil
tonian. a one-dimensional quantum Hamiltonian with inverse-square interacti
on, as the common base. This is because both the eigenvalues of the ensembl
es and a general state of the Calogero Hamiltonian evolve in an analogous w
ay for arbitrary initial conditions. The varying nature of the complexity i
s reflected in different forms of the evolution parameter in each case. A c
omplete investigation of the Calogero Hamiltonian can then help us in the s
pectral analysis of complex systems.