The spectrum and other properties of the PT-symmetric version of
the exactly solvable Scarf's oscillator of type I (= on a finite
interval) are studied. Several interesting observations are made
-- for example, the pseudonorm is found oscillating regularly with
excitation in the manner claimed recently by Duc Thai Trinh as
generic for a slightly different class of potentials.
Unfortunately, the necessary discussion of boundary conditions is,
unexpectedly, declared `` beyond the scope of the present work".
This ``missing link" to the standard functional analysis makes
some of the observations (and, in particular, the ones concerning
certain specific anomalies in PT-orthogonality) slightly
misleading and inconclusive.

MR2252708 Lévai, G. On the pseudo-norm and admissible solutions of
the $\scr{PT}$-symmetric Scarf I potential. J. Phys. A 39 (2006),
no. 32, 10161--10169. 81Q05