Fwd: JDK 9 RFR of JDK-8030942: Explicitly state floating-point summation requirements on non-finite inputs

Fri Jul 18 12:29:41 UTC 2014

Hello Joe,

could you please clarify by short example following assertion:

  154      * If the exact sum is infinite, a properly-signed infinity is
  155      * returned.

I'm afraid I don't quite understand what you mean here by 'exact sum'.

Thank you,
Georgiy.

On 16.07.2014 16:37, Paul Sandoz wrote:
>
>
> Begin forwarded message:
>
>> *From: *Joe Darcy <joe.darcy at oracle.com <mailto:joe.darcy at oracle.com>>
>> *Subject: **JDK 9 RFR of JDK-8030942: Explicitly state floating-point 
>> summation requirements on non-finite inputs*
>> *Date: *July 16, 2014 2:29:46 AM GMT+02:00
>> *To: *Core-Libs-Dev <core-libs-dev at openjdk.java.net 
>> <mailto:core-libs-dev at openjdk.java.net>>
>>
>> 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/ 
>> <http://cr.openjdk.java.net/%7Edarcy/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>.
>>      *
>>
>