A pointwise estimate on the 1-order approximation of G(x0)(epsilon)

摘要

On the basis of Avellaneda O Hua-Lin (1991, Commun. Pure Appl. Math., 44 897-910), a pointwise error estimate on the 1-order approximation of Green function G(x0)(epsilon) defined in K-2 is shown at first. Then based on this estimate and using asymptotic expansion method, an improved approximation of G(x0)(epsilon) and its pointwise error estimate are obtained.