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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MATH-1344) "ZipfDistribution" cleanup
Date Sun, 20 Mar 2016 17:45:33 GMT
Gilles created MATH-1344:
----------------------------

             Summary: "ZipfDistribution" cleanup
                 Key: MATH-1344
                 URL: https://issues.apache.org/jira/browse/MATH-1344
             Project: Commons Math
          Issue Type: Improvement
            Reporter: Gilles
            Priority: Minor
             Fix For: 4.0


* We should avoid hard-coded numbers.
* Inner class {{ZipfRejectionInversionSampler}} should be private.
It is in package scope only for the sake of testing "helper" functions that are not specific
to that implementation.
* The helper functions are
{noformat}
log1p(x) / x
{noformat}
and
{noformat}
expm1(x) / x
{noformat}
but with a special code path if x < 1e-8, where the Taylor expansion
is used.
If this leads to more correct results (or is more efficient), it should be used generally
by moving the optimization to the corresponding "function object" defined in {{o.a.c.m.analysis.function}}
(as is done for e.g. the {{Sinc}} function).




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