Figure 4From: Multigrid method based on transformation-free high-order scheme for solving 2D Helmholtz equation on nonuniform grids Computed solution obtained from HOC and CDS schemes for problem 2. (a) Exact solution. (b) Computed solution by HOC scheme on uniform grids. (c) CDS scheme on uniform grids. (d) HOC scheme on nonuniform grids, 322, \(\lambda=0.8\).Back to article page