W. Eberhard et al., CONNECTION FORMULAS FOR 2ND-ORDER DIFFERENTIAL-EQUATIONS WITH A COMPLEX PARAMETER AND HAVING AN ARBITRARY NUMBER OF TURNING-POINTS, Mathematische Nachrichten, 165, 1994, pp. 205-229
We consider the differential equation () -u'' + chi(x)u = rhop2phi2(x
)u on a finite interval I, where I contains m turning points, that is
here, zeros of phi. Using asymptotic estimates proved by R. E. LANGER
for solutions of () for intervals containing only one turning point w
e derive asymptotic estimates (for rho --> infinity) for a special fun
damental system of solutions of () in I. The results obtained are fun
damental for the investigation of eigenvalue problems defined by () a
nd suitable boundary conditions.