Gilles created MATH-1396:
----------------------------
Summary: Overflows in "UniformIntegerDistribution"
Key: MATH-1396
URL: https://issues.apache.org/jira/browse/MATH-1396
Project: Commons Math
Issue Type: Bug
Affects Versions: 3.6.1
Reporter: Gilles
Assignee: Gilles
Fix For: 4.0
In {{o.a.c.m.distribution.UniformIntegerDistribution}}, several methods will
compute an invalid result when the {{lower}} and {{upper}} bounds are such that
{noformat}
upper - lower
{noformat}
overflows.
Affected methods:
* {{probability}}
* {{cumulativeProbability}}
* {{getNumericalVariance}}
Method
* {{getNumericalMean}}
will return an invalid result when
{noformat}
upper + lower
{noformat}
overflows.
A possible fix is to define instances variables
{noformat}
upperPlusLower = (double) upper + (double) lower;
upperMinusLower = (double) upper - (double) lower;
{noformat}
and use them instead of the respective integer operations in the above methods.
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