Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An efficient multigrid solver for 3D biharmonic equation with a
  discretization by 25-point difference scheme   In this paper, we propose an efficient extrapolation cascadic multigrid
(EXCMG) method combined with 25-point difference approximation to solve the
three-dimensional biharmonic equation. First, through applying Richardson
extrapolation and quadratic interpolation on numerical solutions on current and
previous grids, a third-order approximation to the finite difference solution
can be obtained and used as the iterative initial guess on the next finer grid.
Then we adopt the bi-conjugate gradient (Bi-CG) method to solve the large
linear system resulting from the 25-point difference approximation. In
addition, an extrapolation method based on midpoint extrapolation formula is
used to achieve higher-order accuracy on the entire finest grid. Finally, some
numerical experiments are performed to show that the EXCMG method is an
efficient solver for the 3D biharmonic equation.

25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc