Ported to Java by Shigeru Yoshida for the IceCube MC.
2002.12.1
syoshida@hepburn.s.chiba-u.ac.jp
Before using, initialize the state by the constrctor RandomDouble(long)
in this Java version.
Search the array index such that x is between xx[index]
and xx[index+1]. xx must be monotonic, either increasing
or decreasing. index =0 or index = n-1 is returned
to indicate x is out of range.