938167.fig.0015a
(a)
938167.fig.0015b
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Figure 15: The exterior Neumann problem for Helmholtz equation with RCIP applied to (63). The program demo12.m is used with as in (1), and . The boundary condition of (59) is generated by a point source at . (a) The absolute error in at . (b) The number of GMRES iterations needed to meet an estimated relative residual of .