On Sat, 11 Jul 2015 15:12:29 -0700, Phil Steitz wrote:
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.

Numbers?
IIRC, someone said: "First make it correct, then make it faster (if
necessary)". [I.e. the computation may always be inlined later.]

[And I don't get the "copying to / from the stack"...]

Gilles

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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