Annotation of embedaddon/php/ext/bcmath/libbcmath/FAQ, revision 1.1.1.1
1.1 misho 1: BCMATH FAQ:
2:
3: 1) Why BCMATH?
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5: The math routines of GNU bc become more generally useful in a
6: library form. By separating the BCMATH library from GNU bc,
7: GNU bc can be under the GPL and BCMATH can be under the LGPL.
8:
9: 2) Why BCMATH when GMP exists?
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11: GMP has "integers" (no digits after a decimal), "rational numbers"
12: (stored as 2 integers) and "floats". None of these will correctly
13: represent a POSIX BC number. Floats are the closest, but will not
14: behave correctly for many computations. For example, BC numbers have
15: a "scale" that represent the number of digits to represent after the
16: decimal point. The multiplying two of these numbers requires one to
17: calculate an exact number of digits after the decimal point regardless
18: of the number of digits in the integer part. GMP floats have a
19: "fixed, but arbitrary" mantissa and so multiplying two floats will end
20: up dropping digits BC must calculate.
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