The proposed techniques have been implemented in Fortran 77, and have
been tested on a computer having a DEC Alpha 21264(500 MHz) chip as
the CPU. In FMM, we truncate the infinite series in
(3.22) and (3.26) taking 10
terms and compute the series in (4.6),
(4.8) and (4.10) using the 109 point
generalised Gaussian quadrature formula given in Yarvin and
Rokhlin[83]. Also, we set the maximum number of boundary
elements in a leaf to be 100. The integrals in (3.23) are
computed numerically with Gaussian quadrature. To solve the resulting
matrix equation we use the preconditioned GMRES and adopt the block
diagonal matrix corresponding to the leaves as the preconditioner
following the technique proposed by Nishida and Hayami[62]. In
GMRES we terminate the iteration when the relative error is less than
10^{-5}. The inverse of the preconditioner is obtained with Crout's
method.