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Subject: Re: [boost] [Review Request] Multiprecision Arithmetic Library
From: Christopher Kormanyos (e_float_at_[hidden])
Date: 2012-04-02 16:49:19

>> All the floating point types, have full std lib support (cos sin exp, pow >> etc), as well as full interoperability with Boost.Math. >> >> What is the precision of the following operations: *, /, +, -, sqrt >> for the cpp_dec_float type? > Good question, we don't really guarantee any at present. > In practice they're *usually* accurate to 1eps, > but they're not intended to compete with MPFR's guarantees. > But Chris would know more? My basic operations (add, sub, mul, div) are on-par or faster for a variety of reasons. For example, I don't allocate---just use std::array "on the stack". Those GMP and MPFR guys can not program in a professionally adherent fashion. But they sure do have efficient algorithms! Their square root, exponential, logarithmic and trigonometric functions beat mine hands down. I'd like to get a hold of their algorithms and program them in a readable, portable fashion. I think they use, for example, binary splitting for trigonometric functions, whereas I use Taylor. >> Any limitations on the maximum/minimum value of exponent? > Must fit in a long long.  That still gives some pretty big numbers ;-) In other words, approx. 10^(10^19) for 64-bit long long. The Python language MP stuff has unlimited exponents. I forgot what that thing is called, but it's another cool tool. Best regards, Chris.

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