php-src/ext/bcmath/libbcmath

This is bcmath, a library of arbitrary precision math routines.
These routines, in a different form, are the routines that to
the arbitrary precision calculations for GNU bc and GNU dc.

This library is provided to make these routines useful in a
larger context with less restrictions on the use of them.

These routines do not duplicate functionality of the GNU gmp
library.  gmp is similar, but the actual computation is different.