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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (MATH-387) Duplicate code
Date Mon, 19 Jul 2010 14:59:53 GMT

     [ https://issues.apache.org/jira/browse/MATH-387?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gilles resolved MATH-387.
-------------------------

    Resolution: Fixed

Changed in revision 965509.

Although, because of this:
{quote}
The optimizer that will construct the point does not know beforehand that the convergence
checker selected by the user will use or not the point [...]
{quote}

I now wonder whether it will really be useful to allow "null"!

Another question is whether one can meaningfully separate the optimization algorithm from
the convergence checker: Can one always choose a checker independently of the optimization
algorithm?


> Duplicate code
> --------------
>
>                 Key: MATH-387
>                 URL: https://issues.apache.org/jira/browse/MATH-387
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.1
>            Reporter: Gilles
>            Priority: Minor
>             Fix For: 2.2
>
>         Attachments: RealPointValuePair.java.diff
>
>
> In package optimization:
> {code:title=SimpleRealPointChecker.java|borderStyle=solid}
> public boolean converged(final int iteration, final RealPointValuePair previous, final
RealPointValuePair current) {
>     final double[] p        = previous.getPoint();
>     final double[] c        = current.getPoint();
>     for (int i = 0; i < p.length; ++i) {
>         final double difference = Math.abs(p[i] - c[i]);
>         final double size       = Math.max(Math.abs(p[i]), Math.abs(c[i]));
>         if ((difference > (size * relativeThreshold)) && (difference >
absoluteThreshold)) {
>             return false;
>         }
>     }
>     return true;
> }
> {code}
> {code:title=SimpleVectorialPointChecker.java|borderStyle=solid}
> public boolean converged(final int iteration, final VectorialPointValuePair previous,
final VectorialPointValuePair current) {
>     final double[] p = previous.getPointRef();
>     final double[] c = current.getPointRef();
>     for (int i = 0; i < p.length; ++i) {
>         final double pi         = p[i];
>         final double ci         = c[i];
>         final double difference = Math.abs(pi - ci);
>         final double size       = Math.max(Math.abs(pi), Math.abs(ci));
>         if ((difference > (size * relativeThreshold)) &&
>             (difference > absoluteThreshold)) {
>             return false;
>         }
>     }
>     return true;
> }
> {code}
> Do they do the same thing or am I missing something?
> Also in
> {code:title=SimpleScalarValueChecker.java|borderStyle=solid}
> public boolean converged(final int iteration, final RealPointValuePair previous, final
RealPointValuePair current) {
>     final double p          = previous.getValue();
>     final double c          = current.getValue();
>     final double difference = Math.abs(p - c);
>     final double size       = Math.max(Math.abs(p), Math.abs(c));
>     return (difference <= (size * relativeThreshold)) || (difference <= absoluteThreshold);
> }
> {code}
> it seems overkill that one must create two {{RealPointValuePair}} objects when one just
wants to compare two {{double}}. Shouldn't this class contain a method like
> {code}
> public boolean converged(int iteration, double previous, double current) {
>     final double difference = Math.abs(previous - current);
>     final double size       = Math.max(Math.abs(previous), Math.abs(current));
>     return (difference <= (size * relativeThreshold)) || (difference <= absoluteThreshold);
> {code}
> ?
> Also none of these methods seem to need an {{iteration}} parameter.

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