--------------------------------------------------
From: "Luc Maisonobe" <luc.maison...@free.fr>
Sent: Friday, January 29, 2010 12:49 AM
To: "Commons Developers List" <dev@commons.apache.org>
Subject: Re: svn commit: r904231 - in /commons/proper/math/trunk/src:main/java/org/apache/commons/math/linear/AbstractRealVector.javasite/xdoc/changes.xml test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java

Bill Barker a écrit :


--------------------------------------------------
From: "Luc Maisonobe" <luc.maison...@free.fr>
Sent: Thursday, January 28, 2010 12:14 PM
To: "Commons Developers List" <dev@commons.apache.org>
Subject: Re: svn commit: r904231 - in
/commons/proper/math/trunk/src:main/java/org/apache/commons/math/linear/AbstractRealVector.javasite/xdoc/changes.xml
test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java

Mikkel Meyer Andersen a écrit :
Hi.

Thanks!

Why use an iterator instead of just a simple for-loop? And what about
saving
the values until the vector invalidates - I see pros and cons for both
approaches, so it's more to hear what your thoughts were?

It is because there already are several implementations of the class and
they may use different strategies to access elements. Such iterators
have been introduced by recent changes so I thought it was better to
stick with them now.


+1
There is a case for using the sparseIterator, but that probably makes
the methods overly complicated (since zero values have to be handled
specially).

I did hesitate to add this. I thought adding special getSparseMinIndex
and so on, that would explicitely ignore non-zeros. We can add them too
if you think ignoring zeros is the right thing to do. In that case, we
simply copy the methods and change iterator into sparse iterator, that's
all.


I personally have no interest in getSparseMinIndex. Granted, the iterator for OpenMapRealVector is slightly expensive (does a map lookup for each index), but the more I think about it the less I like using sparseIterator here. This would involve something like:
  if(minValue > 0) {
    //repeat loop with iterator to find a zero value
  }
possibly traversing the vector twice.

For 2.1 I'd just go with this addition, and deal with any user complaints in a later version.

Luc


As for saving the values, we cannot be sure when the vector changes.
Users may do this several ways and we simply did not implement any
control on that.

Luc


Cheers, Mikkel.

On 28/01/2010 8:42 PM, <l...@apache.org> wrote:

Author: luc
Date: Thu Jan 28 19:42:31 2010
New Revision: 904231

URL: http://svn.apache.org/viewvc?rev=904231&view=rev
Log:
added min/max getters for real vectors
For compatibility reasons, these methods have been put in the topmost
abstract class but not in the interface yet. It could be pushed to the
interface when next major version will be released.
JIRA: MATH-334

Modified:


commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractRealVector.java

   commons/proper/math/trunk/src/site/xdoc/changes.xml


commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java


Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractRealVector.java

URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractRealVector.java?rev=904231&r1=904230&r2=904231&view=diff

==============================================================================

---
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractRealVector.java

(original)
+++
commons/proper/math/trunk/src/main/java/org/apache/commons/math/linear/AbstractRealVector.java

Thu Jan 28 19:42:31 2010
@@ -292,6 +292,58 @@
        return d;
    }

+    /** Get the index of the minimum entry.
+     * @return index of the minimum entry or -1 if vector length is 0
+     * or all entries are NaN
+     */
+    public int getMinIndex() {
+        int minIndex    = -1;
+        double minValue = Double.POSITIVE_INFINITY;
+        Iterator<Entry> iterator = iterator();
+        while (iterator.hasNext()) {
+            final Entry entry = iterator.next();
+            if (entry.getValue() <= minValue) {
+                minIndex = entry.getIndex();
+                minValue = entry.getValue();
+            }
+        }
+        return minIndex;
+    }
+
+    /** Get the value of the minimum entry.
+ * @return value of the minimum entry or NaN if all entries are NaN
+     */
+    public double getMinValue() {
+        final int minIndex = getMinIndex();
+        return minIndex < 0 ? Double.NaN : getEntry(minIndex);
+    }
+
+    /** Get the index of the maximum entry.
+     * @return index of the maximum entry or -1 if vector length is 0
+     * or all entries are NaN
+     */
+    public int getMaxIndex() {
+        int maxIndex    = -1;
+        double maxValue = Double.NEGATIVE_INFINITY;
+        Iterator<Entry> iterator = iterator();
+        while (iterator.hasNext()) {
+            final Entry entry = iterator.next();
+            if (entry.getValue() >= maxValue) {
+                maxIndex = entry.getIndex();
+                maxValue = entry.getValue();
+            }
+        }
+        return maxIndex;
+    }
+
+    /** Get the value of the maximum entry.
+ * @return value of the maximum entry or NaN if all entries are NaN
+     */
+    public double getMaxValue() {
+        final int maxIndex = getMaxIndex();
+        return maxIndex < 0 ? Double.NaN : getEntry(maxIndex);
+    }
+
    /** {...@inheritdoc} */
    public RealVector mapAbs() {
        return copy().mapAbsToSelf();

Modified: commons/proper/math/trunk/src/site/xdoc/changes.xml
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/site/xdoc/changes.xml?rev=904231&r1=904230&r2=904231&view=diff

==============================================================================

--- commons/proper/math/trunk/src/site/xdoc/changes.xml (original)
+++ commons/proper/math/trunk/src/site/xdoc/changes.xml Thu Jan 28
19:42:31
2010
@@ -39,6 +39,10 @@
  </properties>
  <body>
    <release version="2.1" date="TBD" description="TBD">
+      <action dev="luc" type="add" issue="MATH-334" >
+        Added min/max getters for real vectors (not yet in the
RealVector
interface for
+        compatibility purposes, but in the AbstractRealVector abstract
class).
+      </action>
      <action dev="luc" type="fix" issue="MATH-338" due-to="Vincent
Morand">
        Fixed automatic step initialization in embedded Runge-Kutta
integrators.
The relative tolerance setting was never used, only the absolute
tolerance

Modified:
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java

URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java?rev=904231&r1=904230&r2=904231&view=diff

==============================================================================

---
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java

(original)
+++
commons/proper/math/trunk/src/test/java/org/apache/commons/math/linear/ArrayRealVectorTest.java

Thu Jan 28 19:42:31 2010
@@ -1308,6 +1308,30 @@
    }


+    public void testMinMax()  {
+        ArrayRealVector v1 = new ArrayRealVector(new double[] { 0,
-6, 4,
12, 7 });
+        assertEquals(1,  v1.getMinIndex());
+        assertEquals(-6, v1.getMinValue(), 1.0e-12);
+        assertEquals(3,  v1.getMaxIndex());
+        assertEquals(12, v1.getMaxValue(), 1.0e-12);
+        ArrayRealVector v2 = new ArrayRealVector(new double[] {
Double.NaN,
3, Double.NaN, -2 });
+        assertEquals(3,  v2.getMinIndex());
+        assertEquals(-2, v2.getMinValue(), 1.0e-12);
+        assertEquals(1,  v2.getMaxIndex());
+        assertEquals(3, v2.getMaxValue(), 1.0e-12);
+        ArrayRealVector v3 = new ArrayRealVector(new double[] {
Double.NaN,
Double.NaN });
+        assertEquals(-1,  v3.getMinIndex());
+        assertTrue(Double.isNaN(v3.getMinValue()));
+        assertEquals(-1,  v3.getMaxIndex());
+        assertTrue(Double.isNaN(v3.getMaxValue()));
+        ArrayRealVector v4 = new ArrayRealVector(new double[0]);
+        assertEquals(-1,  v4.getMinIndex());
+        assertTrue(Double.isNaN(v4.getMinValue()));
+        assertEquals(-1,  v4.getMaxIndex());
+        assertTrue(Double.isNaN(v4.getMaxValue()));
+    }
+
+
    /** verifies that two vectors are close (sup norm) */
    protected void assertClose(String msg, double[] m, double[] n,
            double tolerance) {



---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
For additional commands, e-mail: dev-h...@commons.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
For additional commands, e-mail: dev-h...@commons.apache.org




---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
For additional commands, e-mail: dev-h...@commons.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
For additional commands, e-mail: dev-h...@commons.apache.org

Reply via email to