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Theory and Modern Applications

Table 2 The number of multigrid V-cycles with two schemes and different values of \(\pmb{k=10,50, 100,500,1\text{,}000}\) and \(\pmb{\lambda=0.9}\) for Example 2 , where \(\pmb{e^{-5}=10^{-5}}\)

From: Multigrid method based on transformation-free high-order scheme for solving 2D Helmholtz equation on nonuniform grids

 

k

N  = 16

N  = 32

N  = 64

N  = 128

CDS

10

\(8.4161e^{-3}\)

\(4.2104e^{-3}\)

\(9.2610e^{-5}\)

\(2.6041e^{-5}\)

50

\(8.3413e^{-3}\)

\(4.2390e^{-3}\)

\(9.8707e^{-5}\)

\(2.1374e^{-5}\)

100

\(7.7917e^{-3}\)

\(4.7540e^{-3}\)

\(8.6342e^{-5}\)

\(1.9792e^{-5}\)

500

\(7.6893e^{-3}\)

\(3.6964e^{-3}\)

\(7.4763e^{-5}\)

\(1.4136e^{-5}\)

1,000

\(7.6712e^{-3}\)

\(3.8533e^{-3}\)

\(9.1249e^{-5}\)

\(2.2693e^{-5}\)

HOC

10

\(3.8844e^{-5}\)

\(2.8600e^{-6}\)

\(8.7210e^{-7}\)

\(5.3421e^{-7}\)

50

\(3.2736e^{-5}\)

\(2.9751e^{-6}\)

\(8.1872e^{-6}\)

\(5.3453e^{-7}\)

100

\(3.1673e^{-5}\)

\(2.2360e^{-6}\)

\(8.2453e^{-6}\)

\(5.2198e^{-7}\)

500

\(2.9764e^{-5}\)

\(1.7590e^{-6}\)

\(7.9678e^{-6}\)

\(5.4340e^{-7}\)

1,000

\(4.7337e^{-5}\)

\(3.2187e^{-6}\)

\(7.9711e^{-6}\)

\(5.2891e^{-7}\)