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Posted to issues@commons.apache.org by "Anthony Maidment (JIRA)" <ji...@apache.org> on 2012/09/27 16:20:07 UTC

[jira] [Updated] (MATH-871) math3 SecantSolver can return Double.INFINITE

     [ https://issues.apache.org/jira/browse/MATH-871?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Anthony Maidment updated MATH-871:
----------------------------------

    Description: 
In SecantSolver.doSolve(), I had a situation in which f0 and f1, from computeObjectiveValue() on lines 77 & 78, were the same value.

Then when it calculates the next appromixation at line 101:
final double x = x1 - ((f1 * (x1 - x0)) / (f1 - f0));
The denominator is then zero, and the next approximation is Double.INFINITE.

I was able to work around this in this particular instance by relaxing the accuracy requirements of the solver, although I haven't yet fully tested the downstream implications of this change.

  was:
In doSolve(), I had a situation in which f0 and f1, from computeObjectiveValue() on lines 77 & 78, were the same value.

Then when it calculates the next appromixation at line 101:
final double x = x1 - ((f1 * (x1 - x0)) / (f1 - f0));
The denominator is then zero, and the next approximation is Double.INFINITE.

I was able to work around this in this particular instance by relaxing the accuracy requirements of the solver, although I haven't yet fully tested the downstream implications of this change.

    
> math3 SecantSolver can return Double.INFINITE
> ---------------------------------------------
>
>                 Key: MATH-871
>                 URL: https://issues.apache.org/jira/browse/MATH-871
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.0
>            Reporter: Anthony Maidment
>            Priority: Minor
>
> In SecantSolver.doSolve(), I had a situation in which f0 and f1, from computeObjectiveValue() on lines 77 & 78, were the same value.
> Then when it calculates the next appromixation at line 101:
> final double x = x1 - ((f1 * (x1 - x0)) / (f1 - f0));
> The denominator is then zero, and the next approximation is Double.INFINITE.
> I was able to work around this in this particular instance by relaxing the accuracy requirements of the solver, although I haven't yet fully tested the downstream implications of this change.

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