Hi, Andrew,

One possible way to get ibis::bitvector to use 64-bit words is to
change the typedef of ibis::bitvector::word_t to uin64_t.

Regarding the exact performance difference between using
ibis::bitvector::count and the more straightforward option, I have not
measured it.  I would be curious to see what is the actual difference.

John



On 10/4/12 1:05 PM, Olson, Andrew wrote:
> Never mind explaining the difference, I found the descriptions in the 
> documentation.
> 
> New question.  I was trying to port my code to ibis::bitvector64 and found 
> that it doesn't have the count function implemented.
> 
> error: ‘class ibis::bitvector64’ has no member named ‘count’
> 
> I can do some experiments on 32bit bitvectors, but how much of a speedup 
> would you expect as compared to the straightforward implementation mentioned 
> in bitvector.cpp (bitwise AND followed by cnt())?
> 
> Andrew
> 
> On Oct 4, 2012, at 2:42 PM, Olson, Andrew wrote:
> 
>> Hi John,
>> Can you explain the difference between these two classes?
>> Thanks,
>> Andrew
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