Re: [boost] Large Integer Library

Subject: Re: [boost] Large Integer Library
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2012-06-30 11:02:42

AMDG

On 06/30/2012 07:44 AM, Michael Tryhorn wrote:
> John/everyone,
> 
> I have a few other features and benefits of the Boost.LargeInt library,
> which may preempt some questions.  I'm not sure how Boost.Multiprecision
> compares on these specifically, but I thought they would help:
> 
> * All logical, arithmetic and bitwise operators in Boost.LargeInt
>   have constant, O(1) complexity; except for multiplication ('*'),
>   division ('/') and modulus ('%') which are O(n) on the number
>   of bits in the respective large_int type.  Hence support for non
>   power-of-2 large_ints of 96bits, 160bits or otherwise may
>   be used to improve calculation performance.
> 

That can't be right.  Addition of two n-bit
numbers requires processing all n bits and
is therefore O(n).  The fastest known algorithm
for multiplying two n-bit numbers is slower than O(n).

In Christ,
Steven Watanabe