src/share/classes/java/util/stream/DoubleStream.java

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -468,14 +468,11 @@
      *
      * However, since floating-point summation is not exact, the above
      * code is not necessarily equivalent to the summation computation
      * done by this method.
      *
-     * <p>If any stream element is a NaN or the sum is at any point a NaN
-     * then the sum will be NaN.
-     *
-     * The value of a floating-point sum is a function both
+     * <p>The value of a floating-point sum is a function both
      * of the input values as well as the order of addition
      * operations. The order of addition operations of this method is
      * intentionally not defined to allow for implementation
      * flexibility to improve the speed and accuracy of the computed
      * result.

@@ -483,10 +480,27 @@
      * In particular, this method may be implemented using compensated
      * summation or other technique to reduce the error bound in the
      * numerical sum compared to a simple summation of {@code double}
      * values.
      *
+     * <p>If any stream element is a NaN or the intermediate sum is at
+     * any point a NaN, then the final sum will be NaN.
+     *
+     * If the stream elements contain infinities of opposite sign, the
+     * final sum will be NaN.
+     *
+     * It is possible for intermediate sums of finite values to
+     * overflow into opposite-signed infinities; if that occurs, the
+     * final sum will be NaN even if the stream elements are all
+     * finite.
+     *
+     * If the exact sum is infinite, a properly-signed infinity is
+     * returned.
+     *
+     * If all the stream elements are zero, the sign of zero is
+     * <em>not</em> guaranteed to be preserved in the final sum.
+     *
      * <p>This is a <a href="package-summary.html#StreamOps">terminal
      * operation</a>.
      *
      * @apiNote Elements sorted by increasing absolute magnitude tend
      * to yield more accurate results.

@@ -553,20 +567,21 @@
     /**
      * Returns an {@code OptionalDouble} describing the arithmetic
      * mean of elements of this stream, or an empty optional if this
      * stream is empty.
      *
-     * If any recorded value is a NaN or the sum is at any point a NaN
-     * then the average will be NaN.
-     *
      * <p>The average returned can vary depending upon the order in
      * which values are recorded.
      *
      * This method may be implemented using compensated summation or
      * other technique to reduce the error bound in the {@link #sum
      * numerical sum} used to compute the average.
      *
+     * <p>This method can return a NaN or infinite result in the same
+     * kind of numerical situations as {@linkplain #sum() the sum} can
+     * be NaN or infinite, respectively.
+     *
      *  <p>The average is a special case of a <a
      *  href="package-summary.html#Reduction">reduction</a>.
      *
      * <p>This is a <a href="package-summary.html#StreamOps">terminal
      * operation</a>.