Convert Narya (most of the way) over to a Maven Ant task based build. The

ActionScript bits remain belligerent, but the Java stuff is mostly shipshape.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6222 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/main/java/com/threerings/util/RunningStats.java

@@ -0,0 +1,94 @@
+//
+// $Id$
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2010 Three Rings Design, Inc., All Rights Reserved
+// http://code.google.com/p/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.util;
+
+/**
+ * Calculates live values for the mean, variance and standard deviation of a set of samples.
+ * <em>Not thread safe!</em>
+ */
+public class RunningStats
+{
+    /**
+     * Adds a new sample.
+     */
+    public void addSample (double sample)
+    {
+        // From http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#On-line_algorithm
+        _numSamples++;
+        double deltaToOld = sample - _mean;
+        _mean += deltaToOld / _numSamples;
+        double deltaToNew = sample - _mean;
+        _varianceSum += deltaToOld * deltaToNew;
+        if (sample < _min) {
+            _min = sample;
+        }
+        if (sample > _max) {
+            _max = sample;
+        }
+    }
+
+    /**
+     * Returns the minimum sample added or {@link Double#POSITIVE_INFINITY} if no samples have
+     * been added.
+     */
+    public double getMin ()
+    {
+        return _min;
+    }
+
+    /**
+     * Returns the maximum sample added or {@link Double#NEGATIVE_INFINITY} if no samples have
+     * been added.
+     */
+    public double getMax ()
+    {
+        return _max;
+    }
+
+    public double getVariance ()
+    {
+        if (getNumSamples() == 0) {
+            return 0;
+        }
+        return _varianceSum / getNumSamples();
+    }
+
+    public int getNumSamples ()
+    {
+        return _numSamples;
+    }
+
+    public double getMean ()
+    {
+        return _mean;
+    }
+
+    public double getStandardDeviation ()
+    {
+        return Math.sqrt(getVariance());
+    }
+
+    protected int _numSamples;
+    protected double _mean;
+    protected double _varianceSum;
+    protected double _max = Double.NEGATIVE_INFINITY, _min = Double.POSITIVE_INFINITY;
+}