 Several examples will be provided to illustrate the effectiveness of DAT and compact finite difference schemes in numerically solving heterogeneous Helmholtz equations with variable wave numbers.
<meaning-changed>  Several examples will be provided to illustrate the effectiveness of DAT and compact finite difference schemes in numerically solving heterogeneous Helmholtz equations with variable wave numbers.
 Several examples will be provided to illustrate the effectiveness of DAT using the Mth order compact FDMs with M=6,8 for numerically solving heterogeneous Helmholtz equations with variable wave numbers.