JDK 9 RFR of JDK-8030942: Explicitly state floating-point summation requirements on non-finite inputs
Joe Darcy
joe.darcy at oracle.com
Wed Jul 16 00:29:46 UTC 2014
Hello,
Please review my changes to address:
JDK-8030942: Explicitly state floating-point summation requirements
on non-finite inputs
http://cr.openjdk.java.net/~darcy/8030942.0/
Patch below.
Thanks,
-Joe
--- old/src/share/classes/java/util/DoubleSummaryStatistics.java
2014-07-15 17:26:41.000000000 -0700
+++ new/src/share/classes/java/util/DoubleSummaryStatistics.java
2014-07-15 17:26:41.000000000 -0700
@@ -1,5 +1,5 @@
/*
- * 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
@@ -129,9 +129,6 @@
* Returns the sum of values recorded, or zero if no values have been
* recorded.
*
- * If any recorded value is a NaN or the sum is at any point a NaN
- * then the sum will be NaN.
- *
* <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
@@ -143,6 +140,23 @@
* numerical sum compared to a simple summation of {@code double}
* values.
*
+ * <p>If any recorded value is a NaN or the intermediate sum is at
+ * any point a NaN, then the final sum will be NaN.
+ *
+ * If the recorded values 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 recorded values are all
+ * finite.
+ *
+ * If the exact sum is infinite, a properly-signed infinity is
+ * returned.
+ *
+ * If all the recorded values are zero, the sign of zero is
+ * <em>not</em> guaranteed to be preserved in the final sum.
+ *
* @apiNote Values sorted by increasing absolute magnitude tend to
yield
* more accurate results.
*
@@ -193,9 +207,6 @@
* Returns the arithmetic mean of values recorded, or zero if no
* values have been recorded.
*
- * If any recorded value is a NaN or the sum is at any point a NaN
- * then the average will be code NaN.
- *
* <p>The average returned can vary depending upon the order in
* which values are recorded.
*
@@ -203,6 +214,10 @@
* other technique to reduce the error bound in the {@link #getSum
* 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 #getSum() the sum}
+ * can be NaN or infinite, respectively.
+ *
* @apiNote Values sorted by increasing absolute magnitude tend to
yield
* more accurate results.
*
--- old/src/share/classes/java/util/stream/DoubleStream.java 2014-07-15
17:26:42.000000000 -0700
+++ new/src/share/classes/java/util/stream/DoubleStream.java 2014-07-15
17:26:42.000000000 -0700
@@ -1,5 +1,5 @@
/*
- * 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
@@ -470,10 +470,7 @@
* 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
@@ -485,6 +482,23 @@
* 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>.
*
@@ -555,9 +569,6 @@
* 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.
*
@@ -565,6 +576,10 @@
* 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>.
*
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