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From Phil Steitz <phil.ste...@gmail.com>
Subject Re: [math] random boolean arrays
Date Sat, 11 Jul 2015 22:12:29 GMT
On 7/11/15 3:06 PM, Gilles wrote:
> On Sat, 11 Jul 2015 12:08:16 -0700, Phil Steitz wrote:
>> The code implemented in MATH-1242 to improve performance of KS
>> monteCarloP in-lines efficient generation of random boolean arrays.
>>   Unfortunately, I think the implementation is not quite random (see
>> comments on the ticket).  To verify it, we need to be able to test
>> the random boolean array generation directly.  To do that, we have
>> to either expose the method (at least as protected) in the KS class
>> or add it somewhere else.  I propose the latter but am not sure
>> where to put it.  For speed, we need to avoid array copies, so the
>> API will have to be something like randomize(boolean[], nTrue).
>
> Are you sure that copying is an issue for speed?
> I mean, the randomization will anyways copy new values into the
> array...

The algorithm is used in a tight loop that would be slowed down
considerably by allocating and copying arrays to / from the stack. 
>
>> It
>> could go in the swelling MathArrays class, or RandomDataGenerator.
>> The latter probably makes more sense, but the API does not fit too
>> well.  Any ideas?
>
> Isn't there some relationship with
>   https://issues.apache.org/jira/browse/MATH-1158
> ?

No.

Phil
>
>
> Gilles
>
>
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