A multilevel fast multipole algorithm
for solving boundary integral equation of wave scattering
C. C. Lu and W. C. Chew
In the solution of an integral equation using the Conjugate Gradient(CG)
method, the most expansive part is the matrix vector multiplication. Apply a
matrix directly to a vector require N*N floating point operations. The
Fast Multipole Method(FMM) reduced the operation to N*sqrt(N). In this paper,
we apply a multilevel algorithm to this problem and showed that
the complexity of a matrix vector multiplication is proportional to
N*(log N)*(log N).