FastCap is a three-dimensional capacitance extraction program.

FastCap computes self and mutual capacitances between ideal
conductors of arbitrary shapes, orientations and sizes.
The conductors can be embedded in a dielectric region composed
of any number of constant-permittivity regions of any shape and
size.

The algorithm used in FastCap is an acceleration of the
boundary-element technique for solving the integral equation
associated with the multiple-conductor, multiple-dielectric
capacitance extraction problem.  The linear system resulting
from the boundary-element discretization is solved using a
generalized conjugate residual algorithm with a fast multipole
algorithm to efficiently compute the iterates.