DQFUN: A double-quad precision package with special functions (approximately 66
digit precision).

This package permits one to perform floating-point computations (real and
complex) to double-quad precision (approximately 65 digits), by making only
relatively minor changes to existing Fortran programs. All basic arithmetic
operations and transcendental functions are supported, together with numerous
special functions. The package should run correctly on any Unix-based system
supporting a Fortran-2008 compiler and IEEE 128-bit floating-point arithmetic
(in hardware or software).