Hello.


in class org.apache.commons.math3.linear.RealVector there is the
embedded class Entry which is protected, but it is exposed by method
public Iterator<Entry> iterator() ...

Good catch. Thanks.


My solution:
1. make class Entry public
2. make class RealVector implement Iterable<RealVector<Entry>>

so one can do this:

for (RealVector.Entry e : v) {
  if (Double.isNaN(e.getValue()) ||
      Double.isInfinite(e.getValue())) {
    throw new RuntimeException("roots: inputs must not contain Inf or
NaN");
  }
}

IMO, exposing an "Entry" is a mistake: From a user point-of-view, a
"RealVector" should be a collection of "[Dd]ouble".
IIUC, the "Entry" was meant to allow storage or iteration optimizations
in subclasses.
I think that the current "iterator()" method must be deprecated and
removed; in its place, there should be a

  protected Iterator<Entry> entryIterator()

and a new

  public Iterator<Double> iterator()

(that would use the above method), such that "RealVector" would
implement "Iterable<Double>", as is appropriate for this concept.

Eventually, your use-case would become:
-----
  for (Double e : v) {
    if (e.isNaN() ||
        e.isInfinite()) {
      throw new RuntimeException("inputs must not contain Inf or NaN");
    }
  }
-----

JIRA + diff???

A bug report mentioning the inconsistency is welcome.
A diff is not necessary until we agree on the way to go.


Thanks,
Gilles


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