Re: [boost] [Review] Review of the Accumulators library beginstoday Jan 29

From: Eric Niebler (eric_at_[hidden])
Date: 2007-01-31 13:37:44

John Maddock wrote:
> Matthias Troyer wrote:
>>> This would be particularly useful for parallel computing
>>> applications.
>>>
>>> Is this possible? Would it be difficult to add?
> 
> I agree that this would be highly desirable.
> 
>> Yes, this is definitely needed but I think it will be lots of work to
>> add it, based on my own experience in implementing something like
>> this in our ALPS library for parallel Monte Carlo simulations. I am
>> planning to think about this sometime this year, but believe it is a
>> substantial extension to the library and will not be easy to design
>> right. The problem I see is that preparing an estimate from a
>> sequence of values, and preparing an estimate from a number of
>> estimates of independent accumulators requires different algorithms.,
>> e.g.:
> 
> Right: and for some accumulators the addition of two accumulators may not be 
> possible at all.  But can't we make this a conceptual requirement that if 
> you try and combine two accumulator sets, then each accumulator must have a 
> "combine" method (otherwise you get a compile time error).  The "combine" 
> methods for min/max/sum/count etc are all trivial aren't they - and could be 
> added fairly easily ?  But Eric would know the details :-)

This seems like a workable approach to me. But I've learned to believe 
Matthias when he says something is hard. It usually means I've 
overlooked something. :-)

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com