1# The bcmath library 2 3This is a fork of the bcmath library initially created by Phil Nelson in May 42000. 5 6Bcmath is a library of arbitrary precision math routines. These routines, in a 7different form, are the routines that to the arbitrary precision calculations 8for GNU bc and GNU dc. 9 10This library is provided to make these routines useful in a larger context with 11less restrictions on the use of them. 12 13These routines do not duplicate functionality of the GNU gmp library. The gmp 14library is similar, but the actual computation is different. 15 16Initial library (version 0.1) has been created in 2000-05-21 and then forked and 17bundled into PHP with version 0.2 released in 2000-06-07. 18 19## FAQ 20 21* Why BCMATH? 22 23 The math routines of GNU bc become more generally useful in a library form. By 24 separating the BCMATH library from GNU bc, GNU bc can be under the GPL and 25 BCMATH can be under the LGPL. 26 27* Why BCMATH when GMP exists? 28 29 GMP has "integers" (no digits after a decimal), "rational numbers" (stored as 30 2 integers) and "floats". None of these will correctly represent a POSIX BC 31 number. Floats are the closest, but will not behave correctly for many 32 computations. For example, BC numbers have a "scale" that represent the number 33 of digits to represent after the decimal point. The multiplying two of these 34 numbers requires one to calculate an exact number of digits after the decimal 35 point regardless of the number of digits in the integer part. GMP floats have 36 a "fixed, but arbitrary" mantissa and so multiplying two floats will end up 37 dropping digits BC must calculate. 38 39## Credits 40 41Phil Nelson (philnelson@acm.org) wrote bcmath library. 42 43## License 44 45The bcmath library is released under the GNU Lesser General Public License v2.1. 46
